If the Astron overshoots, you can verify it with an oscilloscope. If indeed
it does that, you can modify the circuit to reduce that.

Why are you using a 35 Ampere power supply for such a small load? It would
be better to use a lower current rated unit. I use a 20 Ampere unit and
have no such problem.

Looking at the diagram, you can put in a capacitor across the reference
voltage at the IC to reduce the turn on speed.

On the other hand, it's possible the problem arises due to too slow a turn
on of the supply. You can do things to improve that also. Also, the supply
may be oscillating. Try connecting a dummy load of, say, a few amperes
across the output. An automobile headlamp can work for that.

Best to verify the actual cause with an oscilloscope before starting to make
modifications.

73, Bob K6DDX