UWO: deadline to accept is ???

[Eno_R]

This might sound like a really stupid question, but I don't know when the deadline to accept my UWO offer is. There is nothing about this on the departmental website OR on the graduate admissions website as far as I can tell. I emailed the grad admissions office, who told me to contact my department about the deadlines. The department contact person in turn told me that I can find all the information in the admission letter. But the deadline is not there! I checked the letter three times now: all it says in terms of dates is I need to complete any outstanding requirements (i.e. send official transcripts) a month before commencing my studies and get a study permit. I am a little afraid I'll annoy the program coordinator if I email them again. I also don't want to just poke around on the portal because the system UWO uses is not the most user-friendly, what if I accidentally reply to my offer before I am ready? 

So what do I do now? Wait a while before asking again? The programs I have not heard from yet release the decisions very late, in early May, so I really need to know if I can wait this long before deciding.

Western folk out there, when was/is your deadline to accept? Is it universal across the university? I am not sure: is April 15th a thing in Canada?  Does it matter if your offer is funded/unfunded?