I haven't checked it officially, but as catechists we begin teaching about angels, especially guardian angels, in the first grade. One of the prayers they are required to memorize is the prayer to their guardian angels. I always tried to teach the kids what the angels might look like (St Padre Pio actually saw and conversed with his guardian angel ) and we suggested they try to use their prayers in the morning &/or evening. It is really wonderful to teach children about the Faith starting with small things, like the guardian angels. I just love it!
This isn't official, but it is in the First Grade syllabus, teachers and students!
I hope this helps! :angel1::