I take my Finasteride every day at 2:45pm. Can I change the time? Will it ruin my effectiveness?

Finasteride can be taken at anytime of the day.  It can be taken with or without food.  It will not lose its effectiveness if taken at different times.  The only advice I have would be to take it at the same time everyday.  

Yes, you can adjust the time you take Finasteride. I also suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

You do not have to be so rigorous about your timing of taking Finasteride,although due to its half-life (the time it takes to break down ) it is best to separate doses by roughly 24 hours (give or take a few hours). 

Ideally you should take finasteride once a day at roughly the same time. I wouldn't vary the time too much each day and stick to a regimen that suits you day to day. 

You can change the time you wish to take finasteride without worry.  Daily dosing is important to maximize the benefits of the drug

It does not matter what time you take your Finasteride. Just make sure you take it daily. Whatever you do ritually everyday is where you should place it.