I dont understand why she is waiting for the water to mature. The biological part is the key. Water itself holds very litle bacterial. I resides in the filter, gravel, and on decor en mass. Moving the old filter to the new tank is a great way to seed. YOu can also put the old substrate into a nylon bag (or pantyhose) and set it on top of the new substrate for an even quicker jumpstart. The best way would have been to siphon the mulm (gunk you gravel vac out) and place in under the new substrate with a dusting of peat moss. That "gunk" is where a good amount of the bacteria resides.
Anywho, using the old tank water in the new tank will help stabalize the ph and temp, keeping the water closer to what the shark and pleco were used to.