It all depends on how quickly you want to make the move - as you mention a transition it doesnt sound like there is a super urgency to it! I also don't know how many hives you have so i will assume that you have small numbers:
I'm a newbie but this is what i would do:
Get one or two, maybe even three, 10 frame medium boxes. Working on one hive at a time:
1) Put the 3 X 10 frame mediums on top of the brood chamber and let the bees draw the foundation out
2) When the foundation is fully drawn put two of the drawn mediums on the base board, shake a few frames of bees in to the two mediums, ensure the queen is down there as well.
3) Put on a queen excluder, then put the10 frame deep above the queen excluder with the other 10 frame medium above the brood chamber
4) The queen should start laying in the bottom mediums and the brood from the deep will hatch and the bees should start back filling
5) When all the brood is hatched remove the deeep and set it aside to allow the bees to rob it of the nectar that they will probably have backfilled with. By this time you should start seeing a nice brood pattern developing in the bottom mediums and nectra being put in the top medium
6) At this point you can do one of two things:
a) Remove the Queen excluder and give her free reign of the three medium boxes
b) leave the queen excluder in place and allow the colony to grow ad put down honey stores
Now, in my opinion, here comes the fun part... you can either transiton to two full 8 frame medium boxes and make one split with the remaining six frames from the medium bodies (needing you to buy two queens) or you have the option to potentially make a few (dependent on brood concentration etc) five frame nucleus hives.
All that from only one hive! then you can either convert all of your ten frame gear to 8 frame (which i would do with the mediums you bought) and potentially keep the ten frame deep for swarms.
Just a newbies thoughts....