Hello Thom and thank you for letting me help you with you question.  Generally speaking, the best time to plant a flowering ground cover is in the spring of early fall.  My preference is spring, because there is lots of time ahead for the young plants to establish before cold harsh weather.  However, fall is good too.  Just make sure that they get enough moisture—especaially if some of those awful temps we just got rid of come back.

You didn’t mention what type of flowering ground cover you wanted.  I will add a fact sheet to the end of the article on different types.  For a low growing, nice smelling ground cover, I prefer a thyme.  Most like full sun, but some will take same shade.  

Make sure that you do a soil test and amend your soil appropriately.  Water them in well and fertilize during the growing season.

https://www.dillsgreenhouse.net/wp-content/uploads/2013/02/Ground-Covers-for-the-Landscape.pdf

https://www.southernliving.com/garden/plants/ground-cover-plants-flowers

Happy Gardening
 

Thanks for the response. I haven't  created a list of plants yet, but I will by  next spring