I took a covid test at home at 12 yesterday and then again at 9 pm tonight. so it was technically over 24 hours but after looking at the box it said not to test again for 36 hours. both were negative but does it matter that i tested before the 36?

The test either did or did not find evidence of infection. By testing so close together you just did not let an emerging infection have time to create detectable antibodies. The next day would be a better use of the test. It often takes 3-4 days after a known exposure to test positive.

Yes, it matters. It can take up to 3-4 days after exposure or 2-3 days onset of symptoms for the home (antigen) COVID tests to become positive. And some never are positive with the antigen tests. If you have symptoms and still negative, speak with your doctor and/or pharmacy about having a PCR test. Good luck.