If I do not file an answer for a complaint - unlawful detainer, how much time I have before the sheriff can evict me?

It depends on when they default you and the Sheriff's posting schedule. At best 12 days, at worst 5.

Unfortunately, there is no exact answer to your question. Part of it depends on how promptly the plaintiff files the follow up paperwork and partly it depends on the Sheriff?s schedule. The countdown goes something like this: You have 5 calendar days to file an Answer from the date you were served. On the 6th day, the plaintiff is entitled to file a Request for Entry of Default and obtain a Writ of Possession from the Court. He can then hand deliver the Writ to the Sheriff?s office the same day. The Sheriff will then send an officer to post a notice at the premises indicating a return date. How soon the officer posts that notice is dependent upon their schedule. On the indicated return date (usually 5 days later), the officer will return with a locksmith and if you don?t voluntarily leave the premises at that time, will have the locksmith open the door and the officer will physically remove you from the premises.

It will depend on how fast the court will grant a default judgment and issue a writ of possession. There is no way to know for sure.