When I was a kid they scheduled school breaks around coffee picking time. If you were old enough to go to school you were old enough to pick coffee, rain or shine didn't matter. God forbid you have too many green cherries (beans) in your basket because coffee sticks hurt like hell in the hands of Papa/Dad/Uncle.
Coffee can handle temps down to upper 50's for short periods but prefer mid 60's-70's, into the 90's and your flowers drop. By the looks of your picture, you'll be able to pot up to 1 gallon in another 2 weeks. Once you get 4 or 5 sets of true leaves you can put in ground or minimum 15 gallon container. The deeper the better and good drainage. Use a good balanced fertilizer and you'll be alright.
If you got a lot of hot sun, use shade cloth or put under a shade tree so it gets filtered sunlight. If really dry air you're gonna have to mist them a couple times a day.
My brother has a couple coffee trees in 30 gallon containers in Jacksonville Fla. going on 4 years now. Got enough humidity in the summer time but he has to bring them into the house during the worst part of winter.
One thing most people don't know about coffee, why the locals call them cherries, there's a layer of sweetness right between the skin and the actual bean. You can pop one of them in your mouth, break the skin, and suck on it for awhile but don't eat the bean because raw coffee beans are very bitter. Not really cherry flavored but sweet, tasty and just a hint of caffeine in them to keep you going as a kid. Might just be an acquired taste for some but for me it brings back memories of simpler times.
Seriously though, a good friends parents live on the Big island and they grow a ton of it. You will be fine with a few single plants but clearly they love that volcanic soil. 
