Tense in the 'Tonight is/will be the first time that clause'

[joham]

Are the tenses in the following two sentences both correct and are the sentences of the same meaning?

Tonight is the first time this year that we're seeing a musical in my favourite theatre.
Tonight will be the first time this year that we've seen a musical in my favourite theatre.

 

[billmcd]

Are the tenses in the following two sentences both correct and are the sentences of the same meaning?

Tonight is the first time this year that we're seeing a musical in my favourite theatre. If "tonight" has arrived and the musical is about to begin or has already begun.
Tonight will be the first time this year that we've seen a musical in my favourite theatre. "Tonight" might or might not yet have arrived, but the musical has not yet begun, and I would make it as "will have seen".

b.

 

[SoothingDave]

I think the use of the present tense can work as long as it is near future. In the morning, you could say "tonight is the..." meaning that night.