Adding 2 inches to arms

Hello.

I am 17, 156 lbs, 181cm and I am skinny-fat. My arms have a lot of fat still, and my waist is ~34 inch.

Currently, my left arm is 12.5in with the fat, and my right arm is 13.1in with the fat. If I remove the fat my arms will probably decrease by 0.75-1 inch.

How long will it take for me to add 2 inches to my arms of muscle?

I have been lifting for 10 months, but I was cutting for the 8 months, and have been bulking since 2 months only.

Thanks!