Oh I know you pain, I have sent DS to nursery at 6mo and his day sleep really went nuts. And really that's not much you can do about it. The worse for me was that I tried to have a routine according to the nursery one but in the end that we're doing different things than they stated on the website (in terms of hours/timing). So I would go with your plan, if it's not going to change during next two months - and if it's not working, just try to work close with nursery to establish a better routine. I wouldn't do it ahead as you will be stressed instead of enjoying your last two months with a baby:).