Typical heath family sod-like roots usually makes these super easy to move. And this example has only been in place less than a year.

in your zone probably any time in dormancy ...

up here where there is real cold [unlike your wimp but cold]... i would do it just after the ground thaws ...

i would just dig an inch or two wider than what was planted ...

ken

ps: instead of how early.. how late???.. 6 to 8 weeks before the heat of summer.. so the disturbed roots can settle before the heat ...