Go for as long as you can before adding fish: got to cycle the tank and build your ammonia tackling bacteria in the filter to get a consistent level of control in the tank, or fish will at least be very stressed and more likely to die. (hunt for cycle info on this site). Read some of the 'articles' (listed on top menu bar of the Planted tank site) there are several about starting up tanks. Many say true cycling could take up to 8 weeks....
Flourish Excel= CO2 in a bottle (great for plants, don't overdo for fish or for plants)
Suggest Flourish Comprehensive or other liquid fert or maybe undergravel pellet fertilizer that slowly dissolves for a month at a time?
Cheap timers available at target: 8 bucks, for consistency and when you are away (don't plug your heater into it though, learn from my mistakes)
In the Nano Tank forum, the first thread listed is a 'sticky' that has bunches of suggestions for nanofish...not all are great suggestions (and the definition of nano for that thread was up to 10 gallons); so make sure to track down the adult size of each fish and whether they like to school (3 or more) for happy living...some say a nano tank is not kind to a true schooling fish, as you can't have a really crowd for them to feel safe in.
Probably top recommended fish for nano tank would be an otocinclus (3 or more
a small small catfish that stays small and that eats algae (bonus!) and is not disruptive to plantings; they like some cover, though (some bushy plant) if you don't have cover (taller plants, a driftwood piece etc.) they will really need their companions for happiness. Shrimp would rock in your tank: but again they would like a chunk of moss or two for hiding, and for coverage for their fry.