I too have worn glasses since I was nine. People with perfect eyesight are so lucky, don't you think?
I have bi-focals but no line. It took me no time at all to get used to them. Am getting new ones in a week or two and plan on getting the no line ones again. Sorry I am not being much help. If you don't get used to them in a timely fashion they should do them over for you however. Best of luck.