Keep in mind that the M1 is only valid for 90-days. There's little value in having it when there's still snow and ice on the ground. From mid-Feb you're going to be something like 30-45 days before you can even take the bike out of the garage. Why chew up the validity period when you get nothing from it?
Try to get yourself booked into an M1X course as soon as you can (most should be taking registrations now and will be filling up quickly) and then arrange to get the M1, say, two to three weeks before that.
If you have a bike in the garage licenced, insured and ready to go and want to take it out sooner you can get the M1 sooner but I would resist the temptation to get out too soon. Untrained, cold asphalt with salt and sand everywhere and people not expecting to see bikes out could be a bad combination.
I don't think there will be any insurance benefit to having had an M1 for any length of time. I suspect that to most insurers an M1 is basically the equivalent to having leprosy...
You have to wait 60 days from getting your M1 to upgrade it to the M2.
If you are sure that you'll pass, then doing the M1 in February means that You will get upgraded right after an April Gearing Up course. So there is something to be gotten from doing it earlier. Of course the weather is still a bit sketchy in April.