How far along in pregnancy do you need to be before it will show up on a home urine test?

Depends on the test: Most commercial home pregnancy tests turn positive when the level of HCG (human chorionic gonadotropin) is above 15-25 depending on the manufacturer. Its best to read the paperwork with the test and it will usually say how many days. In general most turn positive around 2 1/2 weeks after conception, some earlier and some later.