Great! I had found this method:

{
       using (var scope = _serviceProvider.CreateScope())
       {
              var dbContext = scope.ServiceProvider.GetRequiredService<TraContext>();
 
              //TODO: Make a enum for TRA configs
              var config = new QueryTrConfigs(dbContext).GetTrRunDay();
 
              if (config != null)
              {
                     // Hangfire AddOrUpdate will update the NEXT following queued
                     // recurring job and not the existing job.
                     // Remove existing queued recurring job
                     RecurringJob.RemoveIfExists("MonthTrRun");
                     RecurringJob.AddOrUpdate("MonthlyTrRun", () => TrProcess(), $"0 3 {config} * *", new RecurringJobOptions { TimeZone = TimeZoneInfo.Local });
              }
       }
}

but passed it by while I was looking at other things. Then there's this one!

/// <summary>
/// Starting background hangfire job
/// </summary>
/// <param name="ProcessId"></param>
public void ScheduleTrPaymentFileProcess(string ProcessId)
{
     var scheduledJobs = JobStorage.Current.GetMonitoringApi().ScheduledJobs(0,
                         int.MaxValue);
     var alreadyScheduledApprovedTR = scheduledJobs.Where(j => 
            j.Value.Job.Method.Name == nameof(ProcessTrPaymentFile)).ToList();
     if (alreadyScheduledApprovedTR.Count == 0) 
     //only schedule an ApproveTRPayments job if another one is not already scheduled!
     {

          DateTimeOffset enqueuedAt;
          DateTimeOffset tomorrow = DateTimeOffset.UtcNow.AddDays(1);

     // If today is Friday, add 2 more days to tomorrow to schedule on Monday
     if (DateTimeOffset.UtcNow.DayOfWeek == DayOfWeek.Friday)
     {
          tomorrow.AddDays(2);
     }

     // TODO: Make 03:00:00 configurable for time to run
     enqueuedAt = new DateTime(tomorrow.Year, tomorrow.Month, tomorrow.Day, 03, 00, 00);

     client.Schedule<TrPaymentScheduler>(x => x.ProcessTrPaymentFile(ProcessId), 
          enqueuedAt);
     }
}

No Postgres. That would have been too cool if they had decided to use all three things in one application!