What I recommend you do is get the tank set up with conditioned water and get and filter and heater running. Set the heater to 80F. If you don't have a heater, you really need one. Bettas are not coldwater fish, whatever anyone might say.
Once yur tank is all set up, get LOADS of live plants. Lots of fast growing stems like cabomba or elodea. These will help soak up some of the chemical waste (ammonia) that occurs in the tank and will help establish your little eco-system. Just one or two plants won't be enough - you can get enough to totally cover the back and one of the sides. Next, get a small cave of some sort - a fish-safe decoration, a terracotta pot or a carved out coconut are good. Make sure it has no small holes the fish could get stuck in. Give it a wash and pop it in the tank.
Now, you have a choice. Keep the betta in his bowl and do a fishless cycle or move him into the tank and do a fish-in cycle. I would strongly suggest doing a fish-in cycle in this instance, as you already need to do daily water changes in on your bowl and there is no sense in making the poor betta say in that tiny thing much longer. You'll still need to do daily water changes in the bigger tank but he'll have more space to swim and the nasty chemicals won't build up as quickly.
Now all you need is a liquid test kit for ammonia and nitrites and test your water every day. If you get zero for both, that's good! If you get a reading for both, do a big water change of between 50-70%. Keep this up for several weeks until you start getting zero every single day. When that happens, your tank has cycled! Well done.
You might have to clean up some algae because the cycle tends to cause algae to grow, but if you have enough plants it shouldn't be a problem. If you can't get some liquid test kits, you'll have to fly blind which means you need to do 70% a day whether or not you need it. In a normal fish-in cycle you'd need to do 70% twice a day a lot of the time but with one fish and a LOT of plants, you should be fine with just one water change a day.
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