Well, any pruning will delay initial flowering...but tend to also produce more flowering from multiple branches.

We cut ours back every fall to just above ground level and it always returns in full glory over two feet high in full blooms for the hummingbirds. zone 7 Texas

I cut mine back every spring with no problems.

We cut ours back to a few inches because in Dallas they freeze to the ground anyway. The decade+ old plants in full sun are back over 5ft before the end of July. Ones in full shade top out around 3 ft.

Aswesome, thanks for the help.