Get your cycle cadence the same as your run, that way your muscles are already working at the same speed. How do you cycle on the road bike? A more aero position works you glutes which helps with running after cycling.
A lot of practise helps, I haven’t done as many runs off the bike this season but get as many in as possible even if you only run 1 mile.
Are you doing Blenhiem? I have Windor in a weeks time, should be a good race.