It depends on the feedback you receive.
If there is major dispute or discussion related to the content and offering, more time is required to resolve those issues.
I wouldn't post a proposal with unresolved outstanding issues.
With that said, I would recommend submitting your proposal no later than 10 days prior to the voting deadline.
In my opinion, judging from the content of your proposal, you have plenty of time to get your proposal into this voting period.