Ok, in regards ***** ***** toxicity and signs we see with bromethalin, there are 2 avenues of signs. First, at high doses, we can see acute collapse and neurological signs within the 24 hours post ingestion. This is less likely here, but we could still see progressive signs over the next 1-2 weeks. And that would require just 6mg to remain in his stomach to cause. So, a lack of signs just now isn't unexpected but we need to keep up that aggressive treatment approach.
Just to note, we need to watch for any wobbliness, tremors, changes in behaviour, GI upset, leg rigidity and seizures.
Otherwise, if he is 10lbs, then he needs at least 10 grams of activated charcoal and up to 40g. This can be repeated every 8 hours until his vet is open and will just bind any lingering toxin here. Just in case you have the milligrams version of activated charcoal, you can just open the capsules to mix with food or water to syringe feed.
Once his vet is open, we'd want them to start IV fluids to flush this out +/- symptomatic treatment for any signs he may have.....