Hey SKF,
Well, it is that time of year. I have a cow due Wed and another due Sat. and I am already sleep deprived!
The first thing I always question and the first thing my vet questions is the breeding date. You saw the bull breed her, but since you just turned him out with the cows I would wonder how long it had been since he bred cows. If he had a long 'down time' he might just be getting 'flushed out' on his first attempts.
However, you said she has milk, so one would think she IS close to calving. Of course it is common to look for swelling of the vulva, discharge, change in behavior such as staying off by themselves, change in eating habits, udder changes, etc. But, my Dad always taught me to look for a dip on the sides of the tailhead. When you can put your fist in that dip things are about to happen! Not smart enough to know the anatomy and physiology involved (a tendon relaxing?) but it sure has been reliable for me. Maybe DL can help me out here on the anatomy and physiology.
I have induced cows but there are too many train wrecks for me to use induction very often. Before you induce be sure to have her palpated to see if the calf is in position.
As has been mentioned, when in doubt, talk with your vet. That is always your best bet.
Good luck and I hope all turns out well for you and your heifer.
Malinda