hi amanda, i have a planted tank with sand so maybe i can help you out
to start, check ur lighting and see how many watts the bulb is. standard bulbs are usually not strong enough for any plants except java moss and java fern.
for around 100 bucks you could get a T-5 108watt light
if you end up adding plants, you can add them when you start the cycle. the amount of bacteria built up in the filter depends on the amount of ammonia their is at a steady rate. The more ammonia=more bacteria. Adding plants helps to start because you dont have to build as up as big a colony. Why wait till after the cycle when you have built up all the bacteria, just to have the colony shrink from the plants sucking up ammonia?
hope this helps!