Somewhere I read that a good way to remember to flip your mattresses is to do it in the 1st and 6th month. It’s supposed to prolong the life of the mattress.
This is another thing that didn’t pertain to me until I had kids. You can’t flip a water bed.
I decided to flip the kids mattresses the long way in January and flip them the short way in June. So, I’m off to flip, wash, and remake the beds.
Have a great day!
Oh! If you have an extra set of bunk beds laying around you could send them my way. 
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I have never even thought about flipping the kids mattresses! Ooops! I used to flip ours, until my long-legged husband wore a “divet” in his side of the mattress. Now I never flip it from side-to-side or I’ll get his indent.
But I think, in general, we just need a new mattress.
The kids mattresses were not new when they started sleeping on them, so I never thought about it. But Joey is getting a new mattress/box spring set in about a week, so I guess I had better pay attention, if I want the thing to last!
I do mine on a “fall, flip”, “spring, spin” schedule.
Hey I have a set of bunkbeds!! That is what we are sleeping on right this moment!!!
I greatly dislike the chore of flipping matresses espcially my king size one!! That is really hard and I usually end up doing it by myself!! Happy flipping!!