Since the first time we met us we are best friends.
I think that this sentence is incorrect, and I am trying to find a good alternative without having to change everything. What do you think of these options? Please tell me if all of them are grammatically correct and also which one is the most natural and native-live.
- Since the first time we met, we are best friends.
- We are best friends since the first time we met each other.
- We are best friends since the first day we met.
- We became friends on the first day we met.