HSBC ISA Offer - Transfer form before deadline?

I’m planning to transfer funds from Trading212 into a new HSBC Fixed Rate Cash ISA, taking advantage of the current cashback promotion (deadline 11 May).

However, during the ISA application, the transfer process requires a paper form to be posted to me and then returned to HSBC. I’m unsure how this affects eligibility for the promotion, particularly given the deadline.

Has anyone gone through a similar process? Specifically, does the eligibility depend on when the application is initiated, or when the transfer is fully completed?

Offer T&C