Steve Stone wrote:

Sometimes a boiler is designed to delay fuel ignition for a few seconds.

My 10 year old Empire baseboard hot water oil fired boiler uses a
Beckett burner with a Suntec oil pump that includes a fuel control
solenoid that delays sending fuel to the nozzle for about 4 seconds.

Steve

That's not delayed ignition, that's pre-purge. Delayed ignition is when
oil is sprayed, but for whatever reason it does not ignite immediately.
Pre-purge runs just the blower for a few seconds to establish a draft
before it switches on the oil. Pre-purge is usually accompanied by
post-purge which shuts off the oil and keeps the blower on for 10 sec or
so to clear all combustion gasses out the chimney.