How should i slice my time in various activities involved in a startup

First, welcome to the group.

As for your question, there is rarely a one-size-fits-all approach that work. It all depends on the million different variables. You need to see what needs attention first.

Consider a 2x2 matrix which includes what is important vs. not important on one side and urgent vs. non-urgent on the other side. Make sure you take care of the important urgent stuff first.

If you find yourself spending too much time on the urgent non-important stuff, then you know you are trapped into time-wasting activities and you need to restructure things.

Definitely put client calls on the top of your list - it's much more expensive to get a new customer than to keep an existing one.

Thank you so much for your question.

There are two incredibly important angles I need to throw your way. The first is about time management, to be expected. The second is about lead generation/customer retention.

I agree with John about the urgent vs important. However, I don't think we can stress enough that focusing on important tasks is critical. You've probably heard of the 80/20 rule. 80% of your results come from 20% of your effort and time. This is true. So, how do we fill up an entire workday, then, and still feel like nothing was accomplished?

Seemingly urgent tasks. Things like email, phone calls, and meetings come to mind. I disagree that you need to be taking every phone call. Somebody should be, but it doesn't have to be you. And hey, if you can't get to the phone right away because you're vastly improving the UI on the software I license from you, then I'll be happy if you get back to me tomorrow. Be sure to explain this to me, your hypothetical customer, however.

Regarding time management tactics. Schedule everything. I fought this for a long time, but finally giving in to this advice has made a world of difference for me. It prevents thinking about your next task. If it's already written down, just do it, and ignore those pesky emails until a specified time, for a set duration.

Next, customer retention.

If you already have customers, I would work on making them ecstatic about your product and/or service. Spending 10 hours on lead generation is wasteful. Use that time, instead, to interact with your current users, making the product better for them. If somebody inquires about your business, of course, treat them with the same level of attention, but don't go searching for new business.

Focus on making your current clients so happy that they will spread the word about your services.

Watch:
Gary Vaynerchuk on caring your face off

Read:
The Thank You Economy by Gary Vaynerchuk
The 4-hour Work Week by Tim Ferris

well done for getting your business started!

I humbly suggest that nobody else is qualified to tell you how much time to allocate to these activities, if only because only you know how quickly you can complete each one.

Please bear in mind that the most successful people manage their activities, because that is the only manageable element. Time & tide wait for no-one.