Do the math.
This is a great question, and one of the most important issues facing early stage companies. When it comes to ownership, try to quantify everything. This helps to eliminate subjectivity and protect each party involved.
Simply coming up with the IP, the business plan, and early stage work to get to the point that you are currently - this is worth something. I think its worth about 25%. If you did this yourself, you should start with 25%. If multiple people worked on it, they should split it fairly.
If you put money into the project, this is also worth something. Figure out what the valuation of the company was when you put that $8000 into it. I recommend using the expected future earnings valuation - Here's a calculator. Use your expected earnings for each year, and a discount rate of about 45% since its such an early stage product. After you use this method and get a valuation, you can figure out how much ownership $8,000 actually buys. For example, if you get a present value of $200,000 you will do $8,000 / $200,000 = .04 or 4% ownership.
The size of your stock option pool is going to depend on how quickly you can afford to start paying employees. You mentioned that you think you'll add 1 or 2 more people - how much are you going to be able to pay them when you hire them? Will stock options just be a bonus in addition to a competitive salary? Will stock be a compensation for a reduced salary? Or will stock be the only thing you're paying them with, because you can't pay them salary? If your current team can get this company to the point that its generating enough revenue to hire more people, then your stock option pool shouldn't be more than 5-15%. But if you're going to need another full time partner who's going to be working for equity rather than a paycheck, to help you get to the point that you can start paying people, then you may need to have more stock available.
Free labor is the most valuable thing at this point in the game. If you have 3 people who are all working full-time, then they each deserve about 33% ownership. In your case, if these other guys cannot work full-time until you can pay them salary, then they deserve to have much lower equity in the company than you have. If you're not being paid a salary, you deserve to be paid in equity. If you are being paid in salary, you only deserve as much equity as the difference between the salary you deserve and the salary you're being paid. In your situation, let's say that you're working 60 hours a week on this thing, while Co-founder 2 is only working 12 hours a week on it. In this case, you deserve to have much more ownership than he does for the labor component. If he comes on as a full-time only when you can pay him, that makes his labor contribution closer to that of an employee, not a founder.
So, you take these factors all together, and you come up with a formula something like this to determine how much ownership each category is worth:
100% Ownership = IP Creation and Initial Work + Capital Invested + Existing Equity Commitments + Stock Option Pool + Future Labor Commitments by Founders (that are not being reimbursed in salary)
Company Ownership by Category:
IP Creation and Initial Work = 25%
If Co-founder 1 was responsible for 60% of the IP, then he gets .6 x .25 = 15% ownership
If Co-founder 2 was responsible for 40% of the IP, then he gets .4 x .25 = 10% ownership
Capital Invested = 4%
If Co-founder 1 invested $8,000 when the company was valued at $200,000 = 4% ownership
Existing Ownership Commitments - 3%
You mentioned that you're paying Co-founder 3 with 3% equity.
Stock Option Pool = 15%
(Since we think we can start generating sufficient revenue to support future hires with our current team.)
Future Labor Commitments = 53%
This leaves 53% ownership left over to be distributed by time commitment.
If Co-founder 1 puts in 60 hours a week and Co-founder 2 puts in 12 hours a week, we have a total of 72 hours per week.
Co-founder 1 gets 60/72 x .53 = 44.17% ownership
Co-founder 2 gets 12/72 x .53 = 8.83% ownership
Company Ownership by Individual:
Now, this may not be agreeable to Co-founder 2, so you'll probably want to be tactful about how you interact with him. But if he doesn't agree with this distribution, he needs to justify his position with objective, mathematical reasoning, not subjective opinions.
If you need to decrease the size of the stock option pool to give Co-founder 2 more equity, you can do that. In my opinion, equity is what you pay people before you can afford to give them a paycheck. After you can afford to give them a paycheck, I think that you need to very careful about how much equity you give to your employees, because you're going to need that equity to give to investors to get money so that you can grow your company. That isn't to say that you can't pay your later employees in equity, just that you have to be careful how you spend it, because the way you spend your equity in the early days has a massive impact on your options down the road - forgive my bad pun. ;-)
And lastly, I would encourage you personally, as the CEO, to try to stay above 50% ownership for as long as possible. If you go below 50% ownership simply in your negotiations with your 2nd Co-founder, you've already lost control of your company before you took a single investor or reached 3 full-time employees! This is a dangerous way to start your entrepreneurial adventure, because you've lost control from the very beginning. This means that you may have difficulty growing your company and remaining the CEO.
Hope this helps!