You should have a source of ammonia to get a good cycle. You don't want a situation where you have grown some nitrifying bacteria but not enough to handle the waste fish produce, then when the fish get added you get immediate ammonia spike and have to re-cycle your tank. Your ammonia could be as simple as some fish food you let rot or it could be a pure ammonia product.
Keep an eye on the stem plants, despite claims on the bag, eco-complete is actually inert. The only fertilizer it had was whatever was in the water in the bag and as you might imagine that goes away pretty quick. So if you plan to proceed with only root tabs be aware you should be replacing those on some kind of regular schedule. Personally I prefer liquid fertilizer all in one product like Nicolg ThriveC or Aquarium Co-op Easy Green. I actually have both in use on different tanks and they both do a fine job for me. As for water changes. You can do one whenever you feel you need it. The plants by themselves can handle reasonably high levels of ammonia, certainly 4ppm won't do them harm. Fish of course are a different story.
