What’s your score? Sponsoring spouse from Canada takes about 9-12 months. If you want your PRs together, the cleanest way to do it either before you submit EE profile. That being said, if your CRS score is high enough so that adding spouse doesn’t reduce it below the cutoff (when you got the ITA but before submitting final application), then CIC will let you add spouse to the application. If you get married after submitting final application, CIC will let you add spouse to application without recalculation. So I would recommend you go ahead with application.
I have also heard from an immigration attorney long time ago who said CIC will let you add spouse to application even after your CoPR and PR visa is done and you haven’t landed, however more research on this topic is needed. Nov is still 3 months away. If you do accept the ITA and submit application in next 30 days, you still have to get married first and then notify CIC about this addition once you get the marriage certificate. It’s also likely that by the time all the marriage paperwork comes in, you may get the PPR. If CIC adds spouse to the application and then both of you get PPR, then you both get PR immediately, else you have to wait till after Nov to receive ITA and do the same thing again if you decline it now. Also, adding spouse may delay the approval/PR visa a bit since they have to now conduct background check on spouse + medical.
It goes without saying that you need to do the police clearances and medical exam for spouse in that case.
Regarding stepping outside the US; you are going to face the same worry about whether visa will be accepted or not, or if CBP will give you trouble at PoE or not, irrespective of when you decide to do the landing. Your PR visa will be valid one year from medical exam, so most likely Aug 2019 so you will have time to land.