my tank has been running for just over a week now, i added 6 2" gold fish 2 days ago, i am still getting the same test readings of:

amoonia .25ppm
nirtite 0ppm
nitrate 0ppm

should i do a water change or wait till my readings change? also would i need to add more fish (i ahve a 100us gallon tank)

based on your other post, you have an FX5. it will take time
before good bacteria colonizes your media. some people uses
beneficial bacteria for seeding and expedite cycle. you can
try it or you can wait till your gold fish produces enough
waste to be processed and help form good bacteria in the system

i am using beneficial bacteria also, a product called stability

www.seachem.com/Products/product_pages/Stability.html

so when should i do a water change?

try to check the ammonia level of your tap. 0.25 is usually from the tap.
wait till it spike up together with the nitrite. do not clean yet your
filter until it is clogged or restricted. with beneficial bacteria and
fishes, it will be cycled soon.

Dont do a water change until your tank is cycled (ammonia and nitrite 0 nitrates rising. Goldfish are hardy fish and will be ok