How far in training at goal pace for half marathon buildup?

I did the 3 x 2 mile workout yesterday with another runner and got pulled through a little bit faster than I liked (12:37, 12:31, 12:28 with about 3 minutes rest). I am thinking next week I will do some kind of cutdown run or alternate between marathon pace or half marathon pace next week.

I am hoping I didn't run too hard yesterday by going a bit faster than goal half marathon pace (6:20-6:29 per mile).

Thanks for all the tips!