The bioload is basically coming from the creatures inside the tank. Right now your tank has enough to handle your betta. If you plan on adding more creatures to the tank, add them slowly so you don't overwhelm your beneficial bacteria and kill it off. If this is going to be a betta only tank, then your done! Just do your weekly water changes and enjoy your aquatic pet!
As long as the water has been treated, change away! Increase your bioload by adding fish.