Legal Question in Real Estate Law in California

A mortgage company can file a notice of default at anytime after you become delinquent. Usually, however, they do not do so until you are at least 90 days behind, and in some cases will wait even longer.

Don't confuse "usual practice" with legal rights. There are some old (19th-Century) cases denying a lender the right to foreclose when the borrower's payment was only two or three days late, because the loan agreement didn't say "time is of the essence." I'll bet your loan does contain words to that effect......and the lender could, in theory, serve and record a Notice of Default right away, after any grace period in the agreement ran out.

You may be thinking of the borrower's right to reinstate. A borrower can "call off" the foreclosure at any time up to five (I think) business days before the trustee sale by paying all the arrearages, plus penalties, interest, costs, etc. Since it is typically around 110-120 days (and often more) between the Notice of Default and the sale date, a defaulted borrower will have some time to reinstate his loan, if he can scare up the dough.

Lenders are not being terribly aggressive these days (with exceptions, however; there are sharks and wolves out there), partly because they are over-worked with foreclosures and partly because the market for foreclosed properties looks short-term unattractive to them.