Yes, they MAY KNOW by April 1st LATEST - but that doesn't mean they will have completed the work by 0805 a.m. that day to know who will get offers. They will work through their lists in priority, many people will say "yes" to the offers, some may say "no," and it may take a few days before all the offers have been made. Even after that some people may change their mind and later calls will be made to fill in the gaps. Just because they will have information to start with by 1 April doesn't mean that every applicant can call the CFRC (or their Reserve unit) that morning and expect an answer. I would bet that many staff of the CFRCs will be doing nothing on 1 April expect answering the phone to tell people to wait until they are called, and that will add to delays in getting information out. If you are waiting for a call from a Reserve unit, you may in fact have to wait until the evening of Thursday 7 April when the recruiter is working, if they aren't working full time.