I did the same thing. This was my very first experience with a Cichlid holding fry. My Callochromis Stappersii Raspberry Head female just had fry about 2 weeks ago, maybe 3, I lost track LOL - anyway, when I noticed she was holding which ended up being a 3-7 days before she was ready, I actually netted her and put a bowl underneath her in the water - she was so good - and I carried her over to my 10 gallon shrimp tank. She hung out there for a few days and then she started chasing shrimp away, snails away, and would even check out anything on the ground so I knew she was clearing out an area and making sure it was safe. She did this for a couple days and then it was Saturday and I did a water change on the tank and she spit them in the corner in the java moss. So, I missed it!
I was sooo sad, but as I putting plants back in place I seen a little fry swimming and I said "Well hello!" and then there were 5. I left her in the tank for about 1.5 days and then I put her back on the main tank and the little stinkers are growing so fast. Sooo cute. So, I guess when she starts really making the area safe she's pretty ready - oh and I could see them in her mouth so bad that she was holding them over due I think. I would see fins and tails and everything moving around in her mouth as she couldn't even keep it closed it was so full. When she was holding she chased other fish away but when she was ready to spit, she would swim over a piece of food even and the back up and check it over nose to food and make sure it wasn't a threat. Her demeanor was much more aggressive of making things safe around her, if that makes sense to you. Hope that helps.