I find my Humira shots take about 4 days to take effect, then I get a good 7 days, and the maximum benefit tails off quickly after that. Notice the pattern, and tell your rheumatologist so you can get the frequency of injections right for you.
Everyone's experience is different. Some find 2 weeks between shots is fine, although some who have posted here have weekly shots. I really need it weekly, although because of frequent infections am only allowed my beloved Humira every 4 weeks, yes every FOUR weeks!! AAAAAGH (....sob!). Hope you have better luck than me!