This is a tricky one! You certainly don't want these baby roots to dry up, neither do you want to kick-start them into full growth just now.... yes, this is one of those "damned if you do, damned if you don't" times, so common in gardening. You can repot into compost that is VERY slightly moist, just enough to prevent the new roots from becoming dessicated, which can prove a huge setback to the bulb at this stage, but do not actually "water" the pots ... preferrably not until Sept. 1st, Ian's favourite watering time.