Pokemon.com says that Pokémon Bank will become 100% free to use if you already have the application. That means that Pokemon left in the Bank after the timer runs out can be picked up right away or at any other time at no cost. There is no rush to get them to Home, since Home compatibility will stay for an indefinite amount of time, provided you get a Premium Home subscription. Also, as a side note, you could always withdraw Pokemon from Bank even if the timer ran out before the cutoff date of March 27, you just couldn't deposit.
All in all, just make sure that you don't delete Bank, and you will be able to deposit and withdraw whenever you want, free of charge. Hope I helped!
