Legal Question in Civil Litigation in California

If you serve them, and file the proof of service, immediately, you might get away with it.

You need to serve them as soon as possible, before the court sets an Order to Show Cause regarding your failure to serve. This is what is known as a fast track rule, and the judge is supposed to issue monetary sanctions for first time offenders. Get on it, and maybe you won't even get sanctioned.

If the court date is a Case Management Conference you will probably get away with it since you are a non-lawyer. If it is the trial date, the defendants will get a continuance in order to do discovery. The judge will consider the defendants served no matter when it is done, but may impose sanctions on you including dismissing the case. If the Statute of Limitations has not yet run, you could dismiss the old case, pay a new $355 fee, and file a new suit.

serve it and file the proof of service and you'll be fine. If you don't, you'll get notice of an OSC re dismissal.

Don't sweat it. Just get it done.