About how far along do i have to be before it will show on a pregnancy test?

Figure 4 weeks: 4 weeks from the first day of your last period, or 2 weeks after ovulation. Give or take a couple of days.

About 4+ weeks: Usually by the time that one reaches her missed menses, a pregnancy test can indicate an accurate result. Generally a blood test or dr's office test will be more sensitive and reliable early on than a home test. Don't hesitate to repeat the test one week later, or so, if you see a negative result and are fairly confident that you are pregnant.