@lovegrillin does Becky Lynn actually bloom early for you? Mine has always bloomed mid-late for me.
I tried too to add more extra early & late bloomers. But most of my extra early & early bloomers aren't for me. The only extra early one I have is Butterscotch Ruffles.
For late blooming dips you can't beat Olallie. For late tets try North Country Daylilies.
Just remember that just because a breeder registers a plant as very late doesn't mean it will bloom the same for you. If a cultivar consistently blooms at a different time for me I try to add a comment saying when it blooms for me so that others won't be surprised.