Should we incorporate prior to applying to YC?

Hi, i have a genuine question. My Co-Founder and I have great jobs and would be transitioning to our startup idea full time only in case we get pre-seed funding. If we don't get pre-seed we would shelf the idea or keep or work in with much slower tempo. Incorporating without pre-seed investment already being agreed would generate unwanted cost for us. What should we do? Apply to YC, then incorporate if we get in or should we eat the cost and incorporate prior to applying? Thanks