Can any one give any insight as to when the LBS knows the time is right as it would appear if you get it wrong they can withdraw further for longer?
Your intuition is the best indication of when you need to start bringing him along. You're involved, I am not. Although I can advise from what you post, and I read...without being there; I cannot advise you in a straightforward fashion.
Wait and Watch is used a lot during this time...and no one person is the same about coming forward, do more of what works, less of what doesn't; easy does it...remembering each person's journey is not the same..and at the same time take care of yourself and your journey.
OP is entirely correct with his assessment of "mirroring" you husband's behavior.
I promise; you will know beyond the shadow of a doubt when the time is right...the answers are there; you just have to access them within yourself and most importantly, learn to trust yourself.
Much love, HB
Remember, as each person is different, every MLC/Transition is different..what works for one may not work for another. Most of the time it is trial and error for ALL involved.