Recently separated, trying to figure out fair custody arrangement

My wife and I just separated about 3 weeks ago and we're trying to work out custody stuff without lawyers if we can because obviously that gets expensive fast. We have a 4 year old and a 7 year old. She wants Monday through Wednesday with her, I get Thursday through Sunday, and they go to her place after school on Fridays. I feel like that's not equal and Im worried about consistency for them. Is there a baseline standard most people follow?