Slowly add substrate and try best to spread out roots as you go... slowly adding more substrate and allowing more roots to spread out with substrate between. Do your best to not have a large clump of root in center and sorrounded by coco.
almost certainly going to shock the plant... and roots in water are not the same as roots that develop in a solid substrate... they will have to develop the fine hairs to better absorb water from a solid substrate, that are not as predominant when roots are in water-only environment.
So, expect at least some sort of slow-down or a complete stop to above ground growth, temporarily, and if many plants, they may react differently to same process... some may recover faster than others... some may be less bothered to start.