Big businesses that depend on government money, such the phone company, have large and well paid staff to handle the quirks of government rules, changes, and deadlines — but small businesses do not.
Grant opportunities are all too often funded late, and the rules fixed close to the deadline for grant submission. This puts small business at a disadvantage. Yes, you have a few weeks to get the grant written, but you also have a small business to run, and unlike Verizon, you don’t have $400 per hour lawyers and accountants to do the work for you.
So it makes sense to prepare for the grant writing process before the rules are fixed.