No, you can't disrupt.
There're 2 situations you can disrupt..
i. up to 2-3 months (check your NS handbook to confirm) towards
the end of your NS if you're going to university (NUS/NTU/SMU).
Private universities, poly etc. are not accepted.
ii. if you're going to study medicine/dentistry in NUS (you must
first qualify to enter OCS to be a commissioned officer, Pes A/B
and accepted by the SAF to become a Regular/NSF MO upon
graduation)
In the first place - you should NOT have applied for a course in
poly. You will NOT be released for studying there even if
accepted.