I do it every month. We have a lot of toys so it works. I originally wanted to do it every week but I could not keep up So I have like 3 big totes in the playroom and 3 in the family room. We have one tote out each month. Things like her kitchen and blocks are always out.
I switch whenever he’s bored of them- when I Notice he stops playing with them or picks them up and immediately puts them down without playing with it- I have the swap out toys in his bedroom closet. I also switch from room to room sometimes . We play in his bedroom and living room. So I’ll move around toys from his living room toy bins, play pen and bedroom. Even the different environment switch for toys works for us. Also- switch out books as well!
I do it based off what she is currently showing interest in.
I do it every two weeks or so.