Is it advisable to post the available documents for the application (99%) and a post a single document separately once it is available?
There is 1 document which is awaited by us which is holding the PR application submission.
Appreciate response.
It depends on the document - be specific to get a helpful answer. Generally you are better off waiting and applying with the complete set of docs.
Right now, IRCC has said they won't return apps missing certain documents 'due to covid' - but you really MUST write a letter of explanation that you don't have "document X" because "department of X" is not issuing (or massively delayed) due to covid. (And best to include evidence of application for that document). Even then, there have been one or two cases here where applicants say (claim) they did this and their application was returned.
There may be some minor support docs or related you could send later without much risk but as above - if it's a
required document, it's required and submitting without that doc is a risk.
