I had about 30k. Jumped into startup full-time, spent it all, racked up 10k in CC debt, spent a few months doing contract work on the side to keep the lights on, now about a year later ramen profitable and working down the debt quickly.

I think it depends a bit on the product you're building, how long you think it would take to validate, and your safety net (can you get some quick contract work if needed?).