You can use a tape tab to hold your rocket off the blast deflector (if the rocket is light enough).
Or, you could use a clothes pin clipped to the launch rod. Or you could use an old motor casing slipped over the rod, resting on the blast deflector. Or you could place a scrap block of wood between the blast deflector and the tips of the fins. Or you could invent your own device and report back here on how well it works.
You do not necessarily want the rocket (and nozzle) to be close to the blast deflector. If the deflector is made from an electrically conductive material, and if the rocket slides down to where the ignition clips make contact with the deflector, you will short-circuit the ignition system.
Also, if your rocket is configured with a fat, wide base, and that base is too close to a flat deflector, the motor exhaust will squirt out in all directions and cause a Bernoulli-effect between the rocket and the launcher----your rocket will be 'sucked down' onto the deflector. Don't worry, this hardly ever happens.
Mostly, you just want to have as much usable length of launch rod as possible sticking out in front of the rocket. If you launch the rocket from a spot halfway up the rod you will probably encounter an entirely new set of problems. (Can you say 'bunker?')