I know from firsthand experience that a webform will work if no AOR yet.
I filed two PR/spousal applications as representative (one for me and my wife; one for her sister and her husband) and, shortly after sending, I started to worry about signatures on forms requiring signatures. There was a lot on discussion here about signing in the weeks following the IRCCs "online only" edict of September 23. There were YouTube videos about it. We followed the route of print/sign/scan/send, recommended by some. Others planted seeds of doubt after our applications went in, saying they would be summarily rejected if not "digitally" signed. I worried about getting our applications returned after many months because of failure to follow signature protocol. I was particularly worried because I was responsible for getting things right for another couple, who were counting on me not to screw up.
So, I went to work and found a way to add digital signatures to the forms. I completed new forms, all nicely digitally signed. I "raised" a webform for each application adding the new, improved forms. I apologized profusely for being a pest, but emphasized how diligently were were trying to get things right. So, in each case, the webforms were sent hard on the heels of the applications going in. I wanted to get the webforms in BEFORE we received AOR, fearing that there would be no AOR, only a summary rejection, if we had not perfected the manner of signing before the file received an initial completeness review. In each case, I received an acknowledgment of the webform within a day or so and, in time, both applications received AOR. We have now progressed beyond that, having received biometrics and police certificate requests.
The above is a long way of saying you can send webform at any time.