Greek in 4th grade?

My oldest started 4th grade recently. Last year we did spanish all together as a family (salsa videos, youtube videos, spanish games) and are continuing it this year. We also learned the Greek alphabet and DS started the Greek Alphabet Code Cracker workbook from Classical Academic Press. He just finished the workbook and has expressed an interest in going more in-depth with Greek now. I had originally been planning to just learn the alphabet now, and go more into Greek when he’s older, maybe 12 or so. Should I follow his interest and let him start now? If so, what program should we use? We definitely want Koine Greek. He has been doing the workbook independently, and I’d really like him to do more Greek independently if possible, as I have 3 other kiddos. Thanks!