Retainer

1. I'm eating dinner with friends and I keep taking off my retainers: I say:

I took them off three times! Or

I've taken them off three times!

ARe both allowed?

2. I'm thinking about something else rather than the topic at hand: I say:

My mind is not on that right now.

Can this be said?

3. My friend tells me he works 7 days a week. And I say:

And here I had thought you were a slacker.

Or

And here I thought you were a slacker.

Are both permissable?