Looking for your comments and/or suggestions....

Well my older lady friend jeannette is finally going to get her aquarium
starter fish real soon now (I talked about her plans a month or 2 ago here).
She will believe me over lfs employees but I promised her I would ask the
following questions here with you experts (and non-experts) here so she
would feel right about what she will do. Is it o.k. for here to put my (now
hers) seeded sponge prefilter on a penguin biowheel HOB filter on her tank
which has been sitting ready for it, and for her to buy (with my
supervision - I am thinking cherry barbs) 2 or 3 starter fish and for us/her
to put the fish in her tank almost immediately after transporting and
installing the seeded sponge prefilter/filter combo? The lfs lady told her
to put the filter/tank setup together first and let it sit with the filter
running without fish for 2 weeks, then put the starter fish in for another 2
weeks, then the plants for 2 weeks, then more fish 2 weeks after all of
that? The lfs lady doesn't know that I have been running jeannette's filter
in my tank for 2 or more months so we can skip the step about the filter
running for 2 weeks within the tank water without the tank having any fish
in it right? Also - from what I have learned here plants should be put in
before the fish right?

Summary: jeanette has been running her tank with an airstone (18 usa gallon
tank), heater, light for somewhere around 2 months now and I have been
running what is to be her filter, in my tank for a few months now, can we go
to the lfs now, buy the starter fish and plants, come back to my place, put
the filter in her tank, and release the starter fish into her tank? Then
wait 3 or 4 weeks and add the remaining new fish slowly into her tank? Is
her tank water suitable enough for the new fish? I am honoring jeannette by
typing these questions out, any comments or suggestions? Thanks all!