I don't think you need to employ a full-time maid. Due to your son is a full-time K1 student. othewise your maid will become lazy after your son go to school or do other things she like .
Don't worry about the summer holiday usually it around 2 weeks (because my son is the k2 full-time student same situation as you)may be you can put him to your ma or you mother-in-law either one in one week alternative.