not sure how long it takes to make a good cycle of marine aquarium
mine is also 2x1x1
I only cycle it for 1 day ( adding water, salt, PH up, set up the filter )
then I add fish on the very next day

the first fish I add is the ocellaris clown fish (it was only 2 cm when I had them)
even though it's small it's a very strong compare to the others

oh ya btw mine is fish only no corals or sands