First cycle taking camrese. got period half way thru third pack instead of last week on yellow pills. is this normal and is pill still effective?

Yes normal: Sometimes it can take a few months for a cycle to regulate with the birth control pill. Typically by the third pack you're body's adjusted. If you didn't miss a pill, the pill is definitely still effective. I would see what happens the following month. If you still have breakthrough bleeding, an early period, then see your doctor, a different pill may be better for you.