Right now Malf, then pop them in a cool dark place for 8-12 weeks, when the bulbs have popped through about 2-3'' you can bring them out into a coolish room.

make sure you buy bulbs that are suitable for Xmas. they are often descibed as 'prepared' bulbs or 'suitable for forcing' . especially true for hyacinths.

Make sure if they are in bulb pots [no drainage] to use bulb fibre as it doesnt go sour. Place the bulbs so their 'noses' are just above the compost level. when they have been in the dark and their noses are about 1-2" growth bring them out into the light. they will be pale yellow at this stage and when in the light they will green up ok.