when to add driftwood in aquarium, before Oscar or after?

It really won't matter. Like someone else said your Oscar will decide where he wants things to go. Very few plants can survive a Oscar, but you could try something like Java fern or hornwort. I java fern rooted to some small pieces of driftwood in with my Jack Dempseys. They just move the driftwood around lol. A friend of mine has some anubias rooted to lava rock in with his 10in Oscar. His O just picks up the plant and moves it to where he wants it from time to time.... fun to watch.

P.S. Hopefully your tank is big enough. I wouldn't try anything smaller than a 75, though others will say that a 55 is fine. However a 55 is only like 12in wide.... imagine a 10-14in Oscar trying to turn in that...

You can add them whenever. I like to add them before fish since I can rearrange until I get it just right without stressing them with all the movement.

Java ferns and anubias are pretty tough and can live with very low light. I had them in a tank with no light over it, just ambient light from a dim room and about an hour of afternoon sun in 1 corner. Both those plants can be tied to driftwood or rocks, so you won't have to worry about uprooting and can rearrange them as you like. You can bury the roots, but make sure that the rhizome (the bigger part right at the base of the plant that the thinner stringy roots come out of) isn't buried because it will rot and the plant will die.

Get the tank set up and running, all the ornaments etc, then add the fish.

Dont bother with plants. Your baby Oscar may not destroy them right away, but he wont stay 2" for very long. Mine has grown from 2 to 5" in 3 months, and should be 8" in another 3 months.

That leads on to tank size, hope you have enough space, they get big, and they do it quickly. Lots of filtering needed too. 55gal is a minimum, and they should outgrow that in time.

Good Luck with your new Oscar

Ian

It doesn't really matter when you add it. The oscar will decide where it should go and will move it, repeatedly (at least if it's anything like mine). As for plants my suggestion is to use fake plants. With the exception of only the hardiest plants most will not be able to survive with an oscar.

It doesn't matter when You put in the driftwood. The plants... I would reconsider. Your Oscar is going to get BIG... Your plants will not survive Oscar abuse!

Before. The driftwood lowers the ph and it is just safer to introduce them to the ph they will be living in rather than go and change it on them.