I might consider reducing the amount of food offered and the number of times fish are fed to half a dime size amount of food every other day. This can help keep ammonia levels more manageable along with water changes.
I might also consider using a water conditioner/dechlorinator such as PRIME or AMQUEL + they will also address ammonia along with chlorine and chloramines found in many water supplys. PRIME would be my choice and is used by many.
Would not disturb the filter or clean or replace media(pads,cartridges,sponges) for the next three weeks. Bacteria you are trying to develop will be found in large part in the filter and on the material therein and by not overfeeding,, the material should not need cleaning.
A good liquid test kit such as API Freshwater Master kit is a valuable tool and far more accurate than most strip style kits.
Am not a fan of "cycle in a bottle " products for those that don't work only add ammonia producing dead organics to the tank ,(opinions vary.)
A portion of filter material and or a stocking with a cup full of gravel from a friends tank could help speed the process. if this is option,keep the borrowed material wet in dechlorinated water or aquarium water and make the transfer as quickly as possible. Push the stocking of gravel into the substrate of your tank and or add the filter material to your filter and you should benefit in substantial way.