Form 4 paragraph 3 rent increase dates question

Tenancy Types and Management

Hello,
I am presently looking to increase the rent on a 12month AST agreement start date 15.4.2019, that has now gone periodic. There have been no previous rent increases in all that time to date.
Looking at Form 4 it seems straightforward apart from the statement at (3) The first rent increase date after 11th Feb 2003 is......
Do we
(A) leave the date as pre filled as 11th Feb 2003 then add the start date of the new rent proposed(15.6.21)
or
(B) insert the start date of our original agreement (15.4.19) in place of the 11th Feb 2003 then add the start date of the new rent proposed(15.6.21) ?

I am sure that this is simple when you know, but it does seem quite unclear at first reading
Hope you can help