Do it the easy, cheap way
Why bother buying expensive stuff like BioSpira or doing a long complicated ammonia-fishless cycle when you have everything you need in the filter of the big tank?
Set up your tank, with gravel, filters, lights, everything but fish. The day before you get the fish, take the filter media from the big tank and get as much junk out of the filter as you can.
That might mean opening the canister and taking out a sponge and squeezing it in a bucket of tank water. Or, if there is a Hang-On-Back type filter, taking the filter sponge or cartridge out of that and swishing it and squeeze it to get all that dirty junk out.
Your Dad will need to do this for you, he will understand why and he should be very impressed that you know to do this. You do not, under any circumstances, want to mess with the filter without his permission!
Take that nasty brown dirt (bio-slime) and dump it in the new tankand add some to tthe tank's filter. Hopefully there will be so much dirt that you can't see through the tank anymore. This is GOOD dirt!
The next day it will be all clear, add your fish. Test for ammonia and nitrite daily, but you might not see any at all.