19, maybe!
19
You would be 19 years old after April 20 2013.
In March 2013, they would be 19 years old.
18 if you have not yet had your birthday in 2013, 19 otherwise.18 if you have not yet had your birthday in 2013, 19 otherwise.18 if you have not yet had your birthday in 2013, 19 otherwise.18 if you have not yet had your birthday in 2013, 19 otherwise.
19
19
19
19
In January 2013 he will still be 18 but February 1st is his birthday and he will be 19
On your birthday in 2013, you'll turn 19.
He turned 19 on February 1st 2013.
At the time of answering, they would be 19. They would celebrate their 20th birthday this year (2013)