I am a single mom who has joint custody of my 4 kids ages from 12 to 3 I have a child care issue?

I was recently paying $350 per month for child care and the father pays $350 per month well we have shared custody so we do pretty well he don't have to pay child support but I am being garnished from a student loan and I requested it be reduced but it is still causing me not to be able to pay for child care. So I was wondering if I let my 12 yr old and 13 yr old catch the bus home from school its only one bus and 10 min. away and have someone pick up my daughter who is 9 and drop her off with my boys and they stay at home until I get off work which is at 8pm. Then I will only have to find daycare for my 3 yr old. Is that a good idea no criticism please this is really hard and I dont want to loose my job I am on a waiting list for government childcare but for now I have to do something I dont have family to help me and my ex has joint custody and he want help me any ideas for a single mother with no childcare money i will appreciate it.