Mine went at 39 weeks, but I lost my plug about 4 hours before.
I stood up and there was a little gush which shocked me because I didn't have to go toilet!
Mine was also a bit pinky because it was my 'show' as well...
Umm from what I remember I couldn't hold it like pee, and it was a steady leak of just half my waters (mw broke the other half), it kept sorta coming out in little bursts...
From what I remember it smelled kinda like semen... But that is only what I remember...
Monitor it on a pad, see how long it takes to fill it up, if it's rather quick I would ring the mw and they can do tests? Although because mine was pink the mw knew it was my waters and she didn't think I would make the following week to 40 so no test for me.
I know that you can have a leak and the waters can replenish themselves but I think you need a fair bit of bed rest for that, 31 weeks is really, really early! I had a false labour at 32!