The 50/50 you have should work OK, I use mineral salt with my autopot, I’ve used canna, ionic and hydrocrop it needs to clean sediment free nutrients.
I’d turn it on right away, I know the website suggests hand feeding but idk about that?
I potted it just before Xmas and the pic was 8th of January.
Ec seedlings 0.9/1.1ec
Older seedlings.1/1.2ec
Vegging plants 1.2/1.4ec
Flip 1.3/1.5ec
Bud set 1.4/1.6ec
Mid flower 1.6/1.8ec
That’s only a rough guide you’re environment/light type and intensity can/does affect the ec.