West Highland White Terrier Q&A
My Westie is 8 yrs old. His ears did not really stand up till he was about 10-12mo. The right ear stood up a good two months before the left did. Be patient they will.
Also, make sure the fur on the ears (especially the top) isn't too long that it weighs them down. If left like this the ears will bend over permanently.
I had gotten my westie at 8 weeks and her ears were already up. I guess it depends on the dog and yes trimming their ears up will help.