Required Client Deployments Never Kickoff On Time 2012 SP1

Question

SCCM engineers,
With other OSD tools, when you design a deployment to kick off at 8:00pm, you actually get that (or pretty close to it).  With SCCM 2012 SP1, we've never had luck getting required deployments to start on time...which is a problem when you have schedules
and deadlines.
Anybody had any issues with this before in a mid-sized organization (~20k workstations)?
Are there other posts/resources out there I could take notes from?
What is the most realistic expectation from the tool in terms of meeting an assigned start time?
I'd be happy to give any specifics about the configuration if necessary.
Thanks!

Answer 1

Deployment info:
# of Devices in collection:  1
Created - 8/24/14 8:07pm local time
Polling Interval - Default
Available - 8/24/14 8:07pm local time
Assignment schedule - 8/24/14 8:30pm local time
PackageID - HP100674
SMSTS.log - None for timeframe (only previous build's logs).
CAS.log - No references to packageID.
PolicyAgent log - updated @ 8:13pm local.
Raising event:
instance of CCM_PolicyAgent_PolicyDownloadSucceeded{
    ClientID = "GUID:4A0909E0-5556-40D7-9471-6766E339C8CD";
    DateTime = "20140825001332.807000+000";
    DownloadMethod = "HTTP";
    DownloadSource = "****************/SMS_MP/.sms_pol?HP12030D-HP100674-6F6BCC28.1_00";
    PolicyNamespace = "\\\\***********\\ROOT\\ccm\\policy\\Machine\\RequestedConfig";
    PolicyPath = "CCM_Policy_Policy5.PolicyID=\"HP12030D-HP100674-6F6BCC28\",PolicySource=\"SMS:HP1\",PolicyVersion=\"1.00\"";
    ProcessID = 5052;
    ThreadID = 4540;
PolicyAgentProvider.log - updated @ 8:15pm local.
--- [45] __InstanceCreationEvent settings change on object CCM_Scheduler_ScheduledMessage.ScheduledMessageID="HP12030D-HP100674-6F6BCC28".
--- [59] __InstanceCreationEvent settings change on object CCM_TaskSequence.ADV_AdvertisementID="HP12030D",PKG_PackageID="HP100674",PRG_ProgramID="*".
And otherwise, the monitoring reports in SCCM shows In Progress - Program received.
Thank you!