How large of a drop in testosterone throughout the day is normal?

I’ve had 4 tests done. Two in the morning and two in the evening. My specialist is having me take blood tests in the evening which I know isn’t standard. My test levels in the evening 12 hours after waking up are in the low to mid 300s. But my morning tests have me in the 700s. For context I’m in my 20s. The only reason I know my morning levels is because I requested them after learning I’m supposed to take the test in the morning. Considering he’s had my tests done in the evening and recommended treatment base on those levels I have little faith in his word. He’s offered enclomiphene which I have no idea if is truly warranted.