Timing of Motion to set aside Default in CA

[Shiela CA]

Hello.  In order to set aside a default judgment in California, if you were served substitute service but never got it, it says you have 2 years from discovery the default, OR from service of written notice of a default against you.  Does that just mean if they mailed a copy of the default, whether you got that or not, the time starts from that mailing, or do they have to actually Serve it to you?  Any help would be great.