Spring flowering shrub

Hi:I think the first one that comes to mind is the Forsythia. Here is grows insun , shade or part shade.
Some other ones may be Oakleaf Hydrangea, some of the Azaleas/Rhodos, Ribes Sanguineum ( flowering currant )
Flowering Quince. All of course depending on the conditions of your soil; area, lighting etc.
Hope this helps a bit.
Barb

How about a Winter Honeysuckle? Or Viburnum bodnantentse 'Dawn'? They flower even earlier than the ones Blooms has suggested, and get pruned well before your Buddleja gets going! I expect you need to think about what colour you'd like there - you now have suggestions for white, pink and yellow, as well as a rainbow of Azalea or Rhododendrons. Would a Camellia be too big? Or how about a Skimmia?

You know spritzhenry, you thought the same as me. Winter honeysuckle