Hello deadsea02.
Your criminal record is a must. You can send it after you have filed your application, but you will have to submit it eventually. They will ALWAYS ask for a PC

.
We sent our police certificate and medical exam with the application in the hope that it will get processed more quickly. You can wait until you get AIP, which is about the time they will ask you to submit missing forms, i.e. PC and meds. Some people get DM and AIP at the same time, which only happens if you have submitted everything before they are finished processing the sponsor's file. If you haven't sent all the forms, the processing time will become longer.
Hope this helped.
-Saskia