New Rotor Help/Easy Question

I got a brand new pair of front drilled and slotted rotors practically given to me by a friend and am wondering when it comes to replacing rotors, should you do all 4 at the same time or are you fine replacing 2 at a time?

I'm pretty sure the 4 existing rotors I have are original and have 149,000 miles on them. I believe they've been turned twice and I have no issues with them.

Thoughts?

 

There is a minimum thickness stamped on the rotors, if you’ve already turned them twice you might be getting close. But it won’t hurt to take the other set further until you can get them replaced.

 

Thanks man! Appreciate the help!