It sounds like you do have a plan.
Welcome to the forum. I know we here will do everything we can to help.
First make sure the wood and rocks have no sharp edges. You wouldn't want your first new boy to tear fins on rough edges. When planting a tank always plan ahead in placement. I always plant higher plants (or larger bunch, plants along the back length of the tank.) Now most people will float the bunch plants Which I find keeping them in place to be a pain. I always choose my bunch plants with thicker stems and having already grown a good root bunch. I plant them and add Plant tabs when I do. It gives good hides and resting places for my betta. It also defuses the filter discharge. This allows the filter to do it's job but the tank current is dispersed across the higher plants. and keeps the tank calm. I then start planting a few medium and smaller plants to mid ground adding my decor to sides and center of the tank. I finish the tank with smaller plants to the front and sides of the front. (Keep in mind this saying. When planting a tank for betta when you are done planting, IF YOU CAN SEE YOUR BETTA WHEN YOU GLANCE AT THE TANK YOU DON'T HAVE ENOUGH PLANTS. ) Betta love hides and resting places They love to feel safe, and cover overhead from tall plants and lots of hides gives them that safe feeling and no stress.
I also add Flourish once a week to my tanks and the plants thrive. I find myself trimming them every 2-3 weeks (do not use Flourish excel unless you have advanced plants that need that supplement.)
Keep checking your water parameters and when the tank cycles they should be reading Ammonia 0 ppm, Nitrite 0 ppm, and nitrate between 5 and 10 ppm. When your reading are daily in this range for a week the tank has cycled.
When you add your new betta there will be higher readings in these ranges because you have now increased the bio load. First couple of weeks I do 25% water changes every two days, and a 50% water change once every two weeks. As the parameters go back to normal you can cut back the water changes to 25% each week. (Remember that each time you do water changes to add prime or another water treatment to detoxify the water going in to the tank.
I recommend Prime because not only does it detoxify the water but also helps the growth of your beneficial bacteria. (which you need to build up in the filter to deal with breaking down the toxic ammonia, and complete the nitrogen cycle.)
Hope some of this helps. couple of pictures of a few of my tanks.