Ok, first of all, Congrats on getting an interview!
Second of all, there are a lot of variables you should consider for this decision. If you've done any market research, you may be able to tell whether this is the optimal time to enter the market aggressively, or if you could bootstrap it for a couple more years and make a more aggressive move once you're out of school. The reason for this being, there are still a lot of valuable lessons to be gained at school.
That said, if you feel that now is the most appropriate time for your product to launch (there is demand, the market is educated in the sector) and delaying that launch could/would open up room for a competitor or competitors to saturate the market, then try not to be afraid to stand by your belief that this is right for you, difficult though that can be.
IF all the stars have aligned, you are confident in your product and your team and you get accepted to YC, I'd say go for it. The experience is incomparable, and an education can always be completed later and/or elsewhere. Building your own company is extremely education, and having Paul and Sam and the whole YC as mentors is indescribably invaluable.
Good luck man!
