We have filed a lien on 2/26/21 and now the customer saying that they will not pay us until 90 days after this date which will be outside of our timeline to perfect our lien. We would like to send notices as a sort of "count down" so that we have done our due diligence in providing documentation to the customer that they need to pay us before 90 days.
Yes. Aside from demand letters and invoice reminders, you can also send a Notice of Intent to Foreclose to the customer. Consider it a final warning letter that you have filed a mechanics lien and if payment isn't forthcoming, you are ready and willing to file a foreclosure/enforcement lawsuit. This isn't a required under California lien laws, but has proven quite effective at inducing payment before having to go to court.