Legal Question in Real Estate Law in California

The former owners can stay in the house until they receive a 3-day notice to vacate. If the former owners do not vacate within the 3 day period, the new owner must file an unlawful detainer action (eviction) against them. Once served with an summons and unlawful detainer complaint, the former owners have 5 days within which to answer the complaint. If an answer is not filed, the new owners will obtain a default judgment for possession, and obtain a writ of possession. The Sheriff will serve the writ of possession and the former owners must vacate within 5 days, excluding Saturdays, Sundays and holidays or the Sheriff will lock the former owners out. If an answer is filed, a trial date will be set generally within 30 days (depending upon the particular court).

As a practical matter, the process from foreclosure sale to eviction by the sheriff takes maybe three weeks typically, given that courts, sheriffs and others involved in the process are very busy these days. As Mr. Hoffman's answer points out, it can be somewhat quicker if the new owner acts with a sense of urgency, and it often takes quite a bit longer especially if there is an institutional (bank) high bidder, simply because they are bureaucracies. Filing and service of process times are variables here. You might try to find out who the high bidder is and engage in a negotiation. The buyer may want a tenant.