If you are served with a motion in a California Court, and you want to object to the motion being heard on the merits, then you must file objections at the first available time. If you don't you waive your right to object on the grounds not raised.
As stated in Tate v. Superior Court (1975) 45 Cal.App.3d 925:
(5) It is well settled that the appearance of a party at the hearing of a motion and his or her opposition to the motion on its merits is a waiver of any defects or irregularities in the notice of the motion.
See, for instance, Carlton v. Quint, 77 Cal.App.4th 690, which states:
" The record in this case reveals that, his claim of inadequate notice and improper service notwithstanding, Carlton filed an opposition to the motion for summary judgment eight days before the hearing. Moreover, Carlton appeared and argued at the summary judgment hearing. At no time did he request a continuance of the summary judgment hearing or contend he was prejudiced by inadequate notice or service. He simply stated that service had not been made in compliance with Code of Civil Procedure section 1011.
 "It is well settled that the appearance of a party at the hearing of a motion and his or her opposition to the motion on its merits is a waiver of any defects or irregularities in the notice of motion. (Citations.) This rule applies even when no notice was given at all. (Citations.) Accordingly, a party who appears and contests a motion in the court below cannot object on appeal or by seeking extraordinary relief in the appellate court that he had nonotice of the motion or that the notice was insufficient or defective." (Tate v. Superior Court (1975) 45 Cal.App.3d925, 930
In Carlton v. Quint, 77 Cal.App.4th 690, 91 Cal.Rptr.2d 844 (Cal. App. Dist.2 01/14/2000) the Court states:
" In this case, as indicated, despite his claim of inadequate service and notice in his opposition to the motion and at the summary judgment hearing, Carlton did file an opposition to the motion, appeared and argued at the hearing, never requested a continuance of the hearing and never claimed prejudice by reason of insufficient notice or service. Under these circumstances, we conclude Carlton waived any claim of inadequate service or notice assuming, without deciding, that claim had any merit.
 This court understands the dilemma faced by an attorney who claims his client was not properly served with motion papers and/or that inadequate notice of the hearing was received. If counsel is convinced his/her legal position is correct, he/she may appear at the hearing without filing a response to the motion and request a continuance for the purpose of preparing a proper response. If counsel makes a complete record relating to both the defective service and/or inadequate notice and the inability to prepare a proper response, and the court denies the continuance, the record will be well preserved for any future writ proceeding or appeal.
 If counsel is unwilling to take the chance that a continuance will be granted, he/she should file the best opposition possible under the circumstances. The opposition should include counsel's position on the defective service/inadequate notice issue, as well as the merits. The opposition should contain a complete discussion of counsel's position as to why a more complete opposition was not able to be filed (e.g., because the defective notice of motion did not give counsel adequate time to prepare a response). Counsel should then appear at the hearing, object to the hearing taking place because the service was defective and/or inadequate notice of the hearing was received; again explain to the court the prejudice that has been suffered by reason of the defective service and/or inadequate notice; and request a continuance of the hearing so that a proper response to the motion may be filed. Obviously, if the court denies a continuance, counsel should be prepared to argue the motion on the merits. If, however, the steps described in this paragraph are taken, the record will be well preserved for any future writ proceeding or appeal.
 None of these steps was taken by Carlton in this case. Although he did raise the issue of inadequate service in his opposition and at the summary judgment hearing, he nevertheless filed a response to the motion for summary judgment, never claimed he did not have adequate time to prepare a response, appeared at the hearing, argued the merits, never requested a continuance and never claimed he was prejudiced by the defective service or inadequate notice of hearing. As stated, under these circumstances, we conclude Carlton waived any alleged defective service or inadequate notice."