Reckonable residence

Apologies for creating a new thread as I couldnt find an answer to my query.

I arrived in Ireland on a D visa. Does the time period from arrival in the state to getting the first stamp 1 be considered reckonable?

The reason I am asking is because there is a "D" in the dropdown list in naturalization calculator and I was told by someone that that refers to D type visa.

I am sorry if i am not making sense. Until this afternoon, i believed its only the stamps that matter. Someone just mentioned that if you have the correct landing permission, your clock starts ticking from the moment you land in the state.

Will appreciate you guys input.