While adding used water and bio-spira can help with the cycle, the best option is to use an already established filter (or the media from one).
That way you are transfering into your tank a filter pad or pack of ceramic noodles that already has a nice population of bacteria. All set up and ready to go. You might not have enough bacteria for a full load of fish, but you will have enough to support some and then you can build up the fish numbers from there.
I have a spare internal filter that just runs in one of my tanks. If I want to set up a new tank/new filter I just move it in. It may not be big enough for the tank, but it will support a smaller number of fish while the new filter system cycles.
But a couple of small goldfish should be fine for cycling.. you WANT lots of waste and something hardy enough to survive while the filter gets started.
Cheers
Ian