At 8 months, sleep cues become tricky - yawns, etc can mean boredom or be from habit even. And at his age, you want to be dropping the catnap anyway.
I'd not let him nap before 2.5 hours in the am at the earliest. If he's acting sleepy try changing activities, going for a walk, etc. Of course if he keeps fussing you can put him down but I'd try to extend that to at least 2.5 hours, maybe 2.75 eventually. This should help with the early wakings too!
Ideally, at his age, his routine would be (and can be adjusted for a 7am wake time):
Wake 6:30 am
Sleep - 9:15-10:45
Sleep - 1:30-3:30
Bedtime - 7pm