introducing my gerbils, how will I know if they aren't going to fight?

[iplaythesweetelfamber]

I've had my gerbils split for 2 weeks, and I've had them together a few times in between but they didn't seem ready. Today I finally decided to give them a full introduction, I put them in a neutral territory with a small amount of fresh bedding and a little bit of cardboard. So far they have been together for an hour, there is still some chasing and boxing, but they don't seem to be trying to kill each other as they had before. I want to put them back in their tank and remove the divider but I'm not sure when is the best time, I've read online that you shouldn't leave them alone until they nest together, but I don't think they will nest in this foreign territory. Also the gerbils are approximately the same age, and both female. I just got them within the past month (one a month ago, one 2 weeks ago).
I meant I've had them split in the same cage, as in the split cage method - and they have been swapped from one side of the cage to the other several times a day. They still aren't acting calm but they aren't acting overly aggressive either. They keep putting their heads together and then both of them sit still for a minute like that. sometimes they are chasing each other but I think they are trying to establish dominance.