Usually levo is taken first thing with a full glass of water (it can expand in throat) before breakfast and wait about an hour before eating. Or it can be taken at bedtime as long as you've last eaten about 2 to 2.5 hours before.
I would take it in one dose. You can take the two tablets together. It's best for you.
I'll tell you something right now that your doctor has no knowledge of treating someone who is hypothyroid. Due to the fact that he let you choose 50mcg or 75mcg when your TSH is nearly 4. He is another who thinks you are on sufficient when your TSH drops into the top end of the range.
You need sufficient increases every six weeks with an increase of 25mcg to allow your TSH to be 1 or lower. Some of us even need it suppressed.
You have to read and learn otherwise you will have never feel better. Once you feel well with the removal of symptoms you can stay on that dose.
It takes about six weeks for your first dose of levo to be absorbed and it has a long half life.
From now on always get a print-out of your blood tests from the surgery for your own records and so that you can post if you have a query. Also ask for Vitamin B12, Vit D, iron, ferritin and folate tested next time you are due a test.
A blood test should be the earliest possible and fast (you can drink water) and leave about 24 hours between your last dose of levo and the test and take it afterwards. So that you remember, the day before put your levo in another place so that you aren't on automatic pilot and take it before test as it will skew your results and may cause doctor to reduce your meds which will then result in a reduction.
Whatever dose you are on one daily dose is best.