It's just preference bro. Some people prefer arimidex and say not to run aromasin till pct. So if you only have access to arimidex that's fine. I personally wouldn't even take it at a 500mg ew dose unless blood work told me other wise.
You are 3 weeks in.... Unless you have water retention like crazy or itchy nipples then wait a week and get a proper bloodwork to determine your e level and then report back with that to work off of.....
Thank you all for your answers, in any case, armidex will help me in the PCT process_,Im asking it right now because Im told to take it in few hours from the guy who sells me it, and its expensive, if it will help me in the PCT ill buy it anyway to have,but if it doesnt I would tell him to wait untill my bloodwork.Thank you.