I've found that if you are going in with 1 or more partner and you are all doing it full time, then split it out equally. You'll prevent a whole lot of resentment in the long run. Of course, the devil is in the details. For example - if Founder A put $$ in as well as time, then they are probably going to ask for and would be justified in getting more equity than Founder B who is just putting in time. Happy to chat about this in more detail having been through a handful of co-founder situations where we had both success and failure.