The low bioload prob means low levels of NO2
production, so it takes longer to cycle. (When I did my original cycling & keeping NO2
at 2 or less, it took 2 months to get the 2nd phase established!)
Since you have a cycled 10, why not get some stuff from it (best is a used filter, or at least the gunk from the filter) & seed your 20's filter. That should kick start the cycle.
Re: move - how far are you moving? Not too bad just down the street ... major expedition if going across country!