Hi,
The age limit for pilot is 26. I am now 24, just finished my Degree in Engineering last August. I applied for SIA, and they shortlisted me for interview. I manage to get through their 1st and 2nd interview as well as the Medical. Nothing wrong with getting a degree first, I have got a Degree, but make sure you have an Engineering Degree I suppose. Always have a backup plan for yourself and you can handle the stress of the interview well. I met a cadet pilot undergoing his training in Singapore telling us that he finished his degree as well as master and went to work for 3 years before applying for pilot. As long as they feel that you are qualified, they will want you. But as I heard from the cadet pilots as well, the drop out rate from their training program is around 20-25%. If you have a Degree, even if you dropped out, at least you can find other alternative jobs.