I have been induced 4 times and only once was the gel used on me, which was baby #1.
I started contracting straight away with all of them after my waters were broken.
Im talking, i wasnt dilated when they broke my waters. I was about 1cm, but having had so many babies, my cervix was able to be stretched to get in and break my waters.
The three labours where my waters were broken to induce me were 1hr 4mins, 3hrs 20mins and 1hr 14mins.
Sometimes i had a tiny bit of the drip to get me moving more but i was definately contracting when this was done.
I hope it all goes well for you.