The current season of the English Premier League is already going on, and if you start watching it now you will have missed about half of it or so. While there is nothing wrong with starting to watch it during this period of the season, you might want to be better prepared for next season by learning about when it might start once all has been said and is now out of the way. The reason behind this is that following the season from the very beginning gives you a better idea of what is going on and you can get fully invested in the drama and excitement of it in a way that starting it in the middle would never be able to compare to.
You can follow this link to figure out the start date of the next Premier League, but looking into when the current season started can also make it a bit easier for you to figure this out than might have been the case otherwise. The current season that is ongoing started on the 14th of August, and it will continue until the 22nd of May rolls around.
The players generally get a two month break in the months of June and July so that they can recover and fulfill other commitments that they might have. That means that you are well placed to start watching the next season as soon as the first game is played. This is a tradition that has been going on for decades, and it is very quickly starting to become the most popular sporting event in the world due to high viewership numbers in dozens of countries all in all.