Yeah I would definitely wait it out, rehome the pleco, get everything perfect for the next round.
You WILL need another filter in order to not starve your goldies of oxygen. For a 33g tank, an Aquaclear 70 would be perfect. A used one will run just as well as a new one (I've heard of people gettin 15 years of service out of these filters) and will only run you $10 or $15 at most. Put a LF ad in the classifieds here and also one on your local Craigslist. They aren't hard to come by. Plus the media only needs to be changed if it s falling apart (ie every few years) which is a HUGE money saver.
For now just focus on
-Getting rid of the pleco
-Curing your remaining fish
-Getting everything ready for more goldies.
Thankfully having less fish in the tank will help your situation until the ich is cured.
And remember don't rush things... its all too tempting to snatch up a goldfish when you see a perfect one in the store but you will be thanking yourself when you geteverything sorted out before buying more!!!