I don't mean the fussy periods during the infant stages (<3 months), but meltdowns that resemble tantrums.

Lately, LO will do these angry cries that just puzzle me. She does this angry shake, and looks like she's on the verge of crying. I've noticed this behaviour this past week. She's 8.5 months old.

Is this normal? I thought tantrums started after 12 months! When did your LO start having meltdowns?