NO. You use since with a specific point in time mentioned. For example, you could say "since October" or "since October 21" or even "since 10 o'clock this morning". Make sure to use a very SPECIFIC time reference.
Use 'for' with a period of time. Now you can say 'for a month' or 'for a year'.
While we're at it, you should use the persent perfect verb tense to show that your time frame in not finished when using FOR or SINCE. You can only use AGO when you refer to a finished PAST action, and never, ever couple it with FOR or SINCE. You may, however, use expressions with 'for' with the simple past without AGO: I went out with him for 2 months.
Examples: I've worked for many years VS I've worked since 1995.
參考: An ESL/English teacher with many, many years of experience