Good morning...

Thank you for your question at this exciting event.  Here is a wonderful fact sheet on deciduous shrubs that you may find helpful in your search as well as a beautiful publication that lists out a few bloomers, up to May you may find helpful.  However bloom time is very fluid here in Colorado, very weather dependent.  We think your best approach would be to visit your favorite local garden center right before the wedding and select a shrub that looks great at that time to plant.  

https://extension.colostate.edu/topic-areas/yard-garden/deciduous-shrubs-7-415/

https://extension.colostate.edu/docs/pubs/bloom/18-spring.pdf

We hope you have a wonderful wedding and let us know if you have any further questions.  

Mark, CMG 

Jefferson County Master Gardeners