I’m definitely not a strategist and everything is just my opinion but it seems UKR is holding their own in the Bahkmut area without serious reinforcements. If they can make a significant push towards Mariupol, russia will have to respond.
I would think the NATO "eyes in the skies" will keep Ukraine informed of Russian concentration of forces. I can't image they will happen quickly. And, Ukraine will be able to act accordingly. In the meantime, they can continue to work their plan.