How long does it take to get comfortable using prescribed glasses so I don’t feel drowsy or have headaches?

It's very individual. I had been wearing glasses for many years but when I got a new prescription + anti-blue light filter, I couldn't get used to it for months. Prescription itself was an instant relief but the filter sat incredibly wrong with me. I actually got another pair without the filter about a month later that because it was just horrible to me. Now I'm used to them but it took so long...