The first thing to do is to not think about it in terms of 'balancing' your life, but 'integrating' it. Putting the challenge of time with your son and with your business as a balancing act inherently sets up conflict between the two. It may sound like semantics, but thinking of your situation as integrating your various time commitments will change the way you look at this 'balancing' act.

In my 20-year experience in startups, I've always put family first and have never regretted it. Companies come and go ... you can always build another one. You can't create more time with your son.

You will likely lose potential clients/customers, but I'm sure you won't regret putting your son first. The clients or customers that do stick with you and respect your priorities are likely going to be your strongest clients and more likely to come back to you (this has been my experience).

Definitely get help and delegate if that's possible with your particular business. Good luck and enjoy the time watching your son grow.