Thats fine, let your aquascape evolve and take its on path. You will find that plants may need to move to give more space or because they are shadowed by taller plants. OR, you could just get the plants in the tank and leave them to it, just a Little maintenance to keep them healthy but other than that they do their own thing.
Two real key points of aquascaping are....
1: The hards scape, this will give you design a sense of depth,mood,shape realism or wilderness to which you will position your plants around.
2: Is the plant choice. Choose plants that compliment each other in shape and color. Choosing lots of plants that have similar color and leaf shape will look dull and samey. Also think about how the plants will be at the biggest and best ( Most people forget about this ) so that you can choose its neighbors appropriately.
For example, Hemianthus micranthemoides and Micranthemum umbrosum go well together as far as leaf shape go, where as Micranthemum umbrosum and Aponogeton ulvaceus would be hard to look balanced.
WHEN CHOOSING YOUR PLANTS DO YOUR RESEARCH, LOOK AT ITS FULLY GROWN HIGHT AND WIDTH TO MAKE SURE YOU HAVE ENOUGH SPACE IN YOUR TANK FOR IT TO GROW PROPERLY AND TO COMPARE HOW IT WILL GROW ALONG SIDE ITS NEIGHBORS
It'd look stunning if it was left alone!
