Firstbub, they are all different. Jack started those teething signs at 3 months and got his first tooth at 6 months! Tom started the signs at 5 months the day before the tooth cut taking me by surprise. It is very normal for the signs to start around 3 months, but it could take anywhere from a day to 3 months for the first tooth to cut. Generally, but not always, you will know when it's imminent as they get quite grizzly.

Don't worry too much about her fussy feeding. Your bbs should be able to readily adjust supply now. But if she's really off her food and you are getting quite full in between, then I would recommend expressing. It's always good to have a store of EBM in the freezer anyway.