Are there any important steps/documentation that can be taken care of, while a candidate is waiting in the Express Entry (EE) pool, waiting for an ITA.
For instance, get the medical exam done, get police clearance, etc.?
PCC can take a while in any country, so you should work on that.
Employment reference letters from past employers can take a while, so you should contact them now. Wait to get a letter from your current employer.
Order transcripts from completed education now. Scan your degrees or order replacements now. Get your education certificates and credentials assessed now, if necessary.
Compile the exact dates of your travel history for the last 10 years now.
Compile all addresses you have lived for the last 10 years now.
Medicals should only be done after you get ITA, and this should be the last step before you submit your application. The reason is because you must come to Canada within 1 year of completing medicals and the application processing time is between 3-6 months for most applicants. Do your medicals on the day you submit your application, if possible, and use a e-medical provider for faster transmission of results.