Haven't personally taken this medication but as a nurse we inform patients to wait 14 days before testing. Here's some info:
Will the hCG trigger shot affect a pregnancy test?
Since hCG is the hormone that pregnancy tests are detecting, it will affect the results of a pregnancy test. If you test shortly after taking the hCG shot you will receive a positive test and the results will not be accurate. HCG from the trigger shot can remain in your body for up to 14 days after you have received the injection. Your doctor may advise you to wait two weeks before taking a home pregnancy test or he may have you come in for blood work to confirm pregnancy instead. A quantitative beta hCG test can be given to see if your hCG levels are rising. This would be indicative of pregnancy as hCG from the trigger shot should be declining and not rising.
Some women “test out” the hCG by taking a pregnancy test shortly after receiving the hCG injection and testing daily until they no longer get a positive result. While this may be reassuring, this does not guarantee accurate results from a pregnancy test.