Conversation so far:
When was Washington a surveyor?
Washington's introduction to surveying began at an early age through school exercises that taught him the basics of the profession.
Where was Washington a surveyor?
His first experiences at surveying occurred in the territory surrounding Mount Vernon.
What is Mount Vernon?
CANNOTANSWER.
Did he go to school for surveying?
school exercises that taught him the basics of the profession, followed by practical experience in the field.

Question: How long did he do surveying?
Self-contained rewrite: How long did George Washington do surveying?