This is only the second time I try Chinese food.
This is only the second time I have tried Chinese food.
This is the first time we are all together.
This is the first time we have all been together.
This is the first time I am taking a language course.
This is the first time I have taken a language course.
It was the first time I traveled by plane.
It was the first time I had traveled by plane.
Is this the first time you come here?
Is this the first time you have come / been here?
It is the first time that I have worked like this. = I have never worked like this before.
This is the third time that I have told you this rule. = I have told you this rule three times before.
This is not the first time that I have come here. = I have been here before.
It was the first time that I had worked like that. = I had never worked so much in all my life.
this is the first / second / third etc time that + present perfect (has / have + past participle). The present perfect is used because the sentence means From the day I was born up until the present day, I have never done a certain thing i.e. there is a connection between a point in the past (the day I was born) until the present time (i.e. today, the moment I am speaking).
it was the first / second / third etc time that + past perfect (had + past participle). The past perfect is used because the sentence means From one particular moment in the past until another particular moment in the past, I had never done a certain thing.