Start 3 months before the deadline . Stand back from your proposal to critique it yourself. Have other colleagues critique it as well. New investigators do get the benefit of the doubt but their proposals should not be overly ambitious. Leave that for senior level investigators.
Continued progress is good.
But, don't send in your added materials the day before the Study Section meets. Resubmissions must include an Introduction discussing the previous critique and an explanation of how the revised application differs from the initial one. An application that is only slightly changed or is identical to an earlier proposal will not be accepted as a new application. Page limitations are specified for the different types of proposals. Applications that do not conform to these limitations may be returned to the applicant before or during the review process.