What does Victor decide? What does the creature say he will do while Victor is at work?

Victor consents to making a companion for the creature.

"I consent to your demand, on your solemn oath to quit Europe forever, and every other place in the neighbourhood of man, as soon as I shall deliver into your hands a female who will accompany you in your exile."

The creature says that he will monitor Victor's progress while he works.

Depart to your home and commence your labours; I shall watch their progress with unutterable anxiety; and fear not but that when you are ready I shall appear.