my girls are almost 1 year old and i'm trying to put collars on them for the first time! I know! I know! Should have done it sooner, but I didn't. they are not very happy with them on. (even when I gave a yummy treat) any suggestions? should i put in on for short durations of time and then build up? OR just put it on and leave it on? we are traveling with them soon, so I don't have much time!!