Reagan gave a very good answer which will help you realize available options. Do you want honey this season or is your goal primarily building up bees? You can have both if you choose to wait and split late summer or Fall. Of course you will need to help the split out as late summer is usually dearth time and the Fall flow is not as strong as the Spring (speaking of my location). You will need to feed the late split with pollen sub as well.
Being this is your first bees in your first season, you are taking in a large amount of information. You may or may not know that bees have to have both pollen and nectar (or sugar water) to thrive. If you feed both, even in dearth, they will thrive, which has been my experience. And prosper is exactly what you will need before Winter arrives.
For example:
My very first season , this is exactly what I did. I let my hive build up the whole season until late and then split the >strong hive<, making 5 nucs. (Though this was not my plan, another story), I ordered 4 MATED queens and this was during VERY late Fall when I did so! I am happy to tell you, that by following David?s instructions (from barnyard bees), all five not only made it through the winter, ( The one with the original queen as well as the 4 with purchased queens), but came out full speed ahead the following Spring. . It was a fun project! . And remember these are just a couple ideas, there are several ways to make successful splits! Best of luck what ever you decide!
Phillip