Scheduling Custom Timer Jobs

For scheduling daily, use code like this:

SPDailySchedule dailySchedule = new SPDailySchedule();
dailySchedule.BeginHour = 0;
dailySchedule.BeginMinute = 0;
dailySchedule.BeginSecond = 0;
dailySchedule.EndHour = 23;
dailySchedule.EndMinute = 59;
dailySchedule.EndSecond = 59;

job.Schedule = dailySchedule;

That tells SharePoint to run the job any time between 00:00:00 (12:00
AM) and 23:59:59 (11:59 PM) each day. You can make this window shorter
if you need to schedule it during off-peak hours.

You can also run the job hourly using this code:

SPHourlySchedule hourlySchedule = new SPHourlySchedule();
hourlySchedule.BeginMinute = 0;
hourlySchedule.EndMinute = 59;

job.Schedule = hourlySchedule;

Or every X number of minutes using this code:

SPMinuteSchedule minuteSchedule = new SPMinuteSchedule();
minuteSchedule.BeginSecond = 0;
minuteSchedule.EndSecond = 59;
minuteSchedule.Interval = X;

job.Schedule = minuteSchedule;

The Interval is only available on the SPMinuteSchedule class. Setting
it to 15 will run the job every 15 minutes for example.