You can check the RC requirements for account creation at https://beempy.com/resource_costs (thanks to @holger80 for the work).

Currently, claiming and account takes ~9950Giga RC... I have a project account w/ ~3700 SP, and it yields ~7500Giga RC, so not quite enough to consistently claim accounts, but the cost has dropped below 7400 from time to time.

To answer your question, you must pay the RC cost all at once, and can't split it up over multiple days.

Cheers.