Promise Rings?

My boyfriend and I definitely want to get them, but not sure when the timing is right. I'll be starting college in August far away and it'll be the first time we have to deal with distance (he's currently at a local college). I feel like this is a good time since we will be far apart, but have a little reminder around our fingers that we are still one and we will reunite soon. 
Is this good timing? When did you and your SO get yours?