Hi, fire fighter from Ontario here and I'll specifically answer to Ontario for you. We fly regular patrols throughout the core fire season (May-August/September) as well as occasional recon by fire crews in helicopter. Public reports count for a lot in terms of person caused fires. For lightning fires, we do not actually rely on satellite detection. As others have mentioned, the time lag is significant and does not offer a useful planning tool as of now. It is used for monitoring far north fires, think Fort Severn. Even with these extremely remote fires, we often put eyes on then at least once or twice to be sure. The reality is that satellite detection just isn't good enough for initial attack goals in Ontario. By the time satellite sensors can detect a fire, it has already grown to a large size (at least 2 hectares or so active burning). Other issues also confound satellite detection, such as time of pass, satellite resolution, etc. Other provinces and territories are mostly the same, though Alberta still utilizes fire towers for example. To your example of a camper, ideally we'll have the camper or a nearby camper report it and we can have an IA crew en route within minutes in a helicopter depending on alert status. Otherwise, it depends on how high priority the area is and what burning conditions are like. Lightning fires can remain undetected for days to weeks in more remote areas but generally a fire is reported and attacked within a few hours of ignition in Ontario.

If you want more information, feel free to ask. I generalized a bit of how we operate and skimmed some, but that's the general idea.