There's no way of rushing this. You are getting normal readings for an uncycled tank: X ammonia, 0 nitrite and nitrate. Eventually you will start to get a reading for nitrite as well. This, and ammonia, will then drop gradually to 0 while nitrate climbs.
Don't just stop feeding your fish, because they're your ammonia source to feed the filter. You still need a scrap of it else it'll never cycle. I do mean a scrap, like 0.2 or something, because don't forget it's a poison. This is another reason you need to be doing the BIG water changes - try about 70% rather than 50%.
Like I said before, you're potentially in this for the long haul - some filters cycle on a couple of weeks, some have taken a couple of months.
I'm very dubious of any filter aids like king British or Cycle, but you can try them if you really want to.