I just watch the TV mostrar when I can, but I've read the libros and I know that they're super different. Relatively what book are they at in the TV show? Have they figured out who the first A is?

The A's are different in the mostrar and tu do not know who A is por the end of season 1. As for what book they are up to por the end of the 10th episode they have finished book three and from there they are moving in their own direction. Some things are the same such as Ian's body disappearing but they have also introduced characters that are not in the books.
Hope this helps