hi, just to ask ard roughly how long is the wait for the "holy"
letter? my friend says that if u didnt receive the letter from all
3 unis by middle May you should be worried. My results are
ABC/CCS (gp S). I didnt even get the interview letter
(till now ever since application close on
1st April) and i applied almost all engineering courses
in both NUS/NTU.
I receive mine last year at around May 20+
And don't worry, if you are rejected they will send you a letter
slightly later, but likely within the month of May as
well. 
Still got about 3 weeks, take the time to enjoy yourself, be it
at home, at part-time job, or in NS.
Don't stress yourself out like me, worrying about my GPA right
now.