Is sticky yellow discharge from nipples a sign of early pregnancy?

No. A positive pregnancy test is the clearest sign of an early pregnancy. The tests are relatively inexpensive, and accurate. Discharge is only so helpful, kinda like tea leaves. Actual tests are much better at telling you what's going on with your body.
Nipple discharge. No. 2 different things. If you have nipple discharge, is it both breasts? How do you see it? Do you see it as a wet spot on clothing, or when you squeeze?

Related Questions

Why slight milk color discharge from nipples? Can not be pregnancy I got my periods on time.

Nipple Discharge. There are a few common medical conditions that can cause breast fluid leakage. As long as you are not pregnant or haven't been pregnant recently then please go in to see your trusted medical advisor. Some of the conditions can be serious. Please do not ignore this symptom. Read more...
Galactorrhea. This could be due stress, nursing, medications or elevated prolactin level. Consult with a doctor for blood work and a breast exam. Read more...