「ひまがあったら」vs. 「ひまだったら」
 

I have a question about this sentence.

[= If you are free, please come to visit Tokyo.]

I was wondering why it is not ひまだったら、ぜひ東京へあそびに 来てください。instead.

Or is both correct? Then what's the slightest difference between them?

Please kindly help,
ありがとうございます

WhiteDay

They are both correct.

When translated strictly, they are

ひまがあったら : if you have any free time,
ひまだったら : if you are free,