That's tricky. Years ago primary extended from 1st to 8th grades (6 to 14 y.o. aprox.) so English, that started in 6th was primary. Now 6th to 8th have been moved to ESO.
Anyway I just checked with my son and he started in Infantil, so it's really soon.
The real issue is qualification. To really understand and speak English you need to learn pronuntiation properly. And that's the weakest link in our system. Most teachers have no idea how English is really pronounced and wouldn't be able to understand a native speaker to save their lives. It's impossible to learn English from someone that can't understand or speak it.
I believe it was Aguirre that proposed a plan to invite thousands of native speakers to teach English in Madrid. Of course everybody attacked her as usual whatever she says... I don't like her either, but that was a good idea for once.