1since 
/ˈsɪns/ preposition
/ˈsɪns/ preposition : in the time after (a specified time or event in the past) : from (a point in the past) until the present time
▪ I haven't seen him since yesterday. ▪ I haven't eaten since breakfast. ▪ Since the party, she has not spoken to him at all. ▪ The company has been in its present location since the beginning of the century. ▪ We've been waiting for you since 10 o'clock. ▪ We have been friends since [=ever since] college. ▪ The company started as a small local business 10 years ago and has grown a lot since then. [=within that time] ▪ The house was built in 1919. Since that time [=from 1919 to the present], it has changed owners several times.
▪ I haven't seen him since yesterday. ▪ I haven't eaten since breakfast. ▪ Since the party, she has not spoken to him at all. ▪ The company has been in its present location since the beginning of the century. ▪ We've been waiting for you since 10 o'clock. ▪ We have been friends since [=ever since] college. ▪ The company started as a small local business 10 years ago and has grown a lot since then. [=within that time] ▪ The house was built in 1919. Since that time [=from 1919 to the present], it has changed owners several times.
since the year one — see year
since when?
— used to show that you are surprised and often angry, annoyed, or doubtful about what someone has said or done ▪ “I'm a vegetarian.” “Since when?” ▪ “You told me to do it.” “Since when did you start listening to me?” ▪ Since when is it okay to cheat?
