This is the first/last

This is the first time etc
We use the present perfect in sentences constructed with this/it/that is the first/ second!third/only/best!worst etc.
This is the first time that I’ve heard her sing, (NOT This is thefirst time that I
?
This is the fifth time you’ve asked me the same question (NOT This is the fifth tune you ask …)
That’s the third cake you’ve eaten this morning.
It’s one of the most interesting books I’ve ever read.
I’m flying to New York tomorrow. It’ll be the first time I’ve travelled by plane.
When we talk about the past, we use the past perfect in these structures.
It was the third time he had been in love that year, (NOT … the third time he
tenses with This is the last… etc
Present (simple or progressive) and future tenses are both possible with This is the last… and similar structures.
This is the last time I pay / I’m paying for you. (OR This is the last time I’ll pay for you.)
That’s the last letter he gets / he’s getting from me. (OR That’s the last letter he’ll get from me.)
This is the last thing I’m going to say to you.

For more information consult a good dictionary like Langman, Oxford, Merriam Webster, or Collins.