Snow drop bulbs are best transplanted while they still have green leaves after floweres are drooping. Tulips and daffodils are best transplanted when the bulbs are dormant - after the leaves have dried and release easily from the bulb. Flowering bulbs in a pot can be transplanted directly into the ground immediately - just disturb the roots as little as possible. When flowers droop, cut them off so the plant doesn't use it's strength trying to make seeds. Leave the leaves on the bulb until they turn yellow & release easily from the bulb. It is a good idea to give the bulb some bulb fertilizer while the leaves are still green to help build the flower for next year.