You are the first one to wish me a happy birthday!

If there is some one who is the first one to say happy birthday to me

And I want to tell him this, what is the correct way to say it

You are the first one to wish me a happy birthday!

OR

You were the first one to wish me a happy birthday!

Thanks in advance !

If you are speaking immediately after he wished you happy birthday, use “You are the first…”. In fact, usually you would say “You’re the first…”

If you are speaking some time later, use “You were the first…”.

Hi, if I speak just after he has wished me happy birthday, could I also say,‘You are the first one wishing me happy birthday!’

Also if I am letting him know, he was the first one who wished me happy birthday yesterday, can I say,‘You’re the first one having wished me happy birthday!’

Finally “You are the first one to wish me” sounds like an obligation to me. Can you explain this as well!

Thanks

Informally it would be acceptable, but ‘to wish’ is far more common than ‘wishing’ in that situation, because you have to assume the rest of the phrase if you use ‘wishing’: You are the first one (who is) wishing me…

That doesn’t work. I would use:
You were the first person who wished me…

It’s not an obligation, regardless of how you might think it sounds to you.