Looking on the internet deeply has found these results:

Once you came back is the most popular phrase on the web.

once you comes back 125,400 results on the web	Once you came back 1312,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	Once I came back from vacation and he had moved the store. You came back once, so I came back once too. Once Höss came back to the camp, he learnt about the experiment. Once I came back from a run and near the course center I thought In 1996 the Commission once again came back with a new proposal aiming at introduction of a common system. She was going to get food once and never came back. that if Anu is at the front door, I will tell her this. I guess everyone figured once the power came back on, there'd be a message or something.

once you comes back

125,400 results on the web

Once you came back

1312,000 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

Once I came back from vacation and he had moved the store.
You came back once, so I came back once too.
Once Höss came back to the camp, he learnt about the experiment.
Once I came back from a run and near the course center I thought
In 1996 the Commission once again came back with a new proposal aiming at introduction of a common system.
She was going to get food once and never came back.
that if Anu is at the front door, I will tell her this.
I guess everyone figured once the power came back on, there'd be a message or something.