I'd certainly wait until they are showing new growth. I'm not sure how successful you'll be. Your happy lavender very likely is planted in well-drained soil and has deep roots. Some of the roots are under the walkway. Could you just cut them back to fit the space better? If you do go ahead and move them, be sure their new spot drains very well.

You can move it now while it's semi-dormant. Try to keep a large rootball of soil when moving, and make sure you cut your lavender back by half, because it needs to put all it's energy into its roots. If it has to support a large amount of top growth, it would put undue stress on the plant. Do not fertilize.