Google App Maker: date-driven email notifications - google-apps-script

Question

I need to set up email notifications when the current date is 90, 60, and 30 days from an expiration date.
I've solved the problem (know basically what process is necessary) but am struggling to write the code. :/
Here's what I've pieced together from research. I think it's probably close, but I'm sure it's not correct.
Suggestions? Solutions?
function sendAlerts() {
var query = app.models.Customers.newQuery();
var today = new Date();
var expiresOn = new Date();
// query only for non-notified customers with upcoming due date
query.filters.NotificationAttempts._lessThan = ATTEMPTS_THRESHOLD;
query.filters.Notified._equals = false;
query.filters.DueDate._lessThan = expiresOn;
var customers = query.run();
customers.forEach(function(customer) {
var success = sendNotification(customer);
if (success) {
customer.Notified = true;
} else {
customer.NotificationAttempts++;
}
// performance trade off in favor of consistency
app.saveRecords([customer]);
});
function sendNotification_(to, subject, body)
{
MailApp.sendEmail({
to: 'beth#egaassociates.com',
subject: 'Expiration approaching',
body: 'You have a license, certification, or immunization expiring soon!',
noReply: true
});
}
}
/**
* Creates a time-driven trigger.
*/
function createTimeDrivenTriggers() {
// Trigger on set schedule.
ScriptApp.newTrigger('sendAlerts')
.timeBased()
.everyMinutes(2)
.create();
}
google.scripts.run.createTimeDrivenTriggers();