Dose the tank with ammonia. add 2ppm/gal. twice a week. Yo will still have to do water changes because nitrate will build up. If you have live plants they will use most of the ammonia which is OK as they will also it when fish are added. All other things being equal in two tanks except that one has live plants and the other doesn't is the one without plants relies almost entirely on bacteria to handle ammonia while the tank with the plants will have them consuming more of the ammonia than bacteria will.
The more plantas there are and the faster they grow, the more of the ammonia they will handle. So if you add 2 ppm of ammonia into the empty Q tank, the plants will use most of it. What they cannot use before the bacteria do so determine how much bacteria there will be.
When you know that you are about to get new fish which will go into the tank, change to adding 2 ppm and testing for ammonia. As soon as it tests .25 ppm of lower, redose the 2 ppm. When you are about to get the fish, do a big water change, as big as you can. The plants will have grown during the no fish time and there will be less bacteria as a result. But the tank will still deal with the ammonia OK.
As for water changes you have to do them in tanks with no live plants as nitrate will build up. Eventually it could stall the cycle. You can probably get awat with doing about 50% once a week. Use dechlor when you do so. With enough live plants they will consume any of the nitrate the bacteria make. With enough plants they will use up all the nitrate.
However. most incoming water contains small amounts of things the tank, even those with plants, do not use. Changing water prevents these sort of things from building up with bad results. So, do the water changes at least every 2 week for that reason.
One last word of caution. Some plants are sensitive to ammonia above lower levels. Usually, these are ones kept in high tech planted tanks, but some of such plants can also be kept in moderate light levels. So, if you have more fine leaved or demanding plants. keep an eye on them when adding ammonia. It should be obvious if they are doing badly as a result.
I usually want to keep only plants that are not planted in the substrate in a Q tank. This means either attached to rocks or wood etc. or potted. They need to be easily removed when the time comes to catch the fish in it. I would suggest the two best option for a Q tank are bare bottom or a light colored sand. These make it easier to monitor poop, uneaten food and any expelled worms or parasties.
The bacteria do not need to have "food" every day. However, if they are not getting any ammonia for a number of days in a row, they will "know" this and they will go dormant until ammonia again becomes available. By adding 2 ppm every 3 or 4 days, they will not go dormant. Research into waste water treatment revealed something interesting. The incoming water fluctuates in its ammonia level. It turns out this effective pulsing of ammonia actually made the bacteria more resilient/stronger.
Finally. it is a lot easier to add ammonia every few days than to have fish in the tank to keep it cycled. Fish have to be fed, water has to be changed and the tanks needs to be vacuumed. And when new fish arrive, you have to move out the fish used to keep the tank cycled and then round them up again and return them when the time comes to move the fish in Q into their permanent home(s).
