Lilies should be planted as soon as possible. Do not allow the bulbs to dry up or get moldy or mushy.
I would plant them once the rain has stopped and the ground not soggy.

Plant into a generous hole and mix a bucketsworth of very well rotted compost/manure with the soil before filling in.

Mark the spot so you don't skewer your treasures later. (It happens...)

You can overplant with spring annuals but make it possible to mulch again in spring when the soil has warmed up. They LOVE being fed well.

Pot them up temporarily.