You would have received information regarding pre-arrival programs (funded by IRCC) in both your PPR email as well as along with CoPR. You can join one of their online/in-person session to get detailed information about life in Canada (Employment, Banking, housing, driving, documentation, etc.).
To answer your questions:
The best time is very subjective. There is no universal answer to that.
List of essential documents:
CoPR/Passport
2 Copies of list of accompanying goods
2 Copies of list of goods to follow
CBSA declaration card
Proof of funds
Apart from these, you might want to carry additional documents like your (and your dependents) educational records, certificates (marriage, birth, educational/training etc.), child’s immunisation and school records (if applicable), etc.