Hey,
I would recommend just going to a police station and doing it there. No need to pay the fee at all since it's free if you do it at a police station. I live in Ontario so I went to an OPP station and got it done. (Make sure you go to one that has the electronic fingerprinting. Perhaps call in advance to ask them if they do)
I got an RCMP request on Friday Feb 24th. I couldn't go on that day so I went on Monday Feb 27th. Exactly a week later by Monday Mar 6th I had the RCMP envelope in my mailbox. Keep in mind that I live in the middle of no where so if you live in a relatively big city then you'll probably get it sooner.
When you get it, I used the DCN number for the number that they request. As for the expiry date I put 6 months ahead of the issue date.
Good luck!