I normally get mine arrive the day after it appears on the newstand. Only once has it arrived late and that was January when I could really have done with seeing it before we went to the boat show.
Mailing of the magazine will be somewhat separate to editorial and, I suspect, somewhat separate to subscriptions. I suggest that when your magazine does arrive, email subscriptions and tell them about the problem. They're sure to want to know and unless they know there's a problem, they won't be able to do anything about it. Just cancelling your subscription won't tell them there's a problem so it won't go away. You'll just buy the mag off the newstand and pay more. IPC won't be the loser, you're local newsagent will gain. Guess who'll lose out?