I had GD (diagnosed-ish, no one actually said it, at about 35 weeks) which was mostly diet controlled but sometimes my readings were all over the place, sometimes fine. Even managed to lose 3lbs. I had a meeting with a consultant at about 37 weeks who said just continue with the diet, then another consultant at 39 + 3 weeks said they didn't want me to go over my due date so booked me in one day before my due date for an induction.
Anyhoo, my waters broke that morning at 7am and had my daughter by emergency c-section at 11.35pm the day after after a massively failed induction so my point being they might not do anything about an induction until quite close to your due date, I just assumed they wouldn't do anything so was quite shocked to leave my meeting on the Wednesday with an induction date of the next Saturday.
Can I just say its an utter pain in the arse to be induced! You are monitored throughout active labour so you can't have an active birth, I had three drips and if like me you have a failed induction, 3 prostin gels then full strength syntocin and still only 4cm dilated after nearly 40 hours, a natural birth may be the better option!
Good luck all.
P.S. I met a woman at the HV clinic who had her son on the same day as me, also diagnosed with GD. Her growth scans indicated a big baby 9lb+ but after being induced her bubs weighed 5lbs so these growth scans are literally nonsense.