Delayed creation of Platform Sensor Entities

Hi,
I’m developing an interface to an alarm system and when I connect to it, because of the various protocols involved, it can be a few minutes before I get the information needed to create the sensor entities in Home Assistant.
I create a Component and then a sensor Platform like this
discovery.load_platform(hass, “sensor”, “mydomain”, {}, base_config)
I plan to add additional platforms in future for lights etc
Please can someone help me, how do I delay the creation of the sensor platform (if I need to) and then create sensor entities when I get the information. I do not want to hold up the initialisation of HA while I get the information from the alarm.
Thankyou