4 months should be a decent time to contact/order GCMS.
Btw, why doubt your application? You are already R10 pass (completeness check that happens before you get BIL). If you believe your documentation was done right, don't worry at all. I'm saying this because I'm a diabetic and I was worried about not even getting past MEP - I read a lot about PFL on this forum and it was incredibly helpful.
I stopped worrying as I learned more and more. Fortunate/Unfortunate for me, I was thinking about not even looking at GCKey for another 3 months after UCI change - but got my RFV way before that. I spent most of my Feb, March and April figuring out housing. I already have a Canadian job, but I'm helping my spouse with their job search and things are a bit rushed here. I was thinking to start looking for housing, spouse's job, etc around end of April - so this mean't a lot of deviation for me.
You are FSW-O like me, here's what you can do to make your transition smoother to Canada post PPR:
1. Figure out 2-3 cities where you'll (and your dependent, if any) get a job. See volumes of jobs available, take 1 hour calls with people in your target job title (better if they are immigrants as you can learn a lot more) + city(s) - map this part out.
2. If you are thinking GTA/GVA, it is fine - but then figure out neighbourhoods where you'd like to live and see what rent/mortgage you'd like to pay. Rent is going to hurt you a lot more as a new immigrant. The issue you are likely to face is people won't even rent out a decent place to you without a proof of income. See what you can do here and what your best options are. Airbnbs can cost you a lot - if job + housing both are going to take 2 months+ how'll you manage that stress? It literally breaks down newcomer PRs.
3. Do you have a kid? See areas where you'd like them to attend schools (you'll literally have to live close to those schools) and figure out daycare if you need it. People are waiting for months for daycare right now.
4. Planning to bring on a pet? Well, join my party. There are so many surprises here.
5. Figure out car license. Might as well learn everything you need to pass the writing test. Because, why not?
6. If you got #1, #2, #3, #4, and #5 covered - then look at the nice stuff that Canad a has to offer? You like to run, cycle, canoe, etc? You like to experience culture? You like to party? Want to spend first few years networking and growing professionally? You need to see where you can get those things - that's why you are moving right. Build a life for yourself.
I might have missed so much while writing the list above. But as you can guess, it is quite a lot of work. Settling is a very long journey and the earlier you start, the better you'll be.