Collarbone area, OUCH! Wrist- also ouch! On those areas, I don't think you'd need to wait. If it was on your stomach, thighs or anything that can become loose/wrinkly, I'd recommend against that.
I can't help you since I've yet to get a tattoo while losing weight. Been spending all my money on clothes and not enough for a tattoo, LOL.
Can I ask what you're planning to get or maybe surprise us with a picture later after you get it?
I have 5 tattoos- one on the wrist/forearm, one on my chest above the breast/just below the collar bone, one on the side of my calf, one on the foot and another on my upper back/shoulderblade area and they all look good. It totally depends on where you get it.