Taking your child to the movies has two concerns 1. As mentioned the noise level. I took my child at 2.5 years 2. The type of movie. I took my child to simple and pleasant animations to start off with.

The movie theater per say will not harm the child. The decibel levels may not be suitable and hence ears need to be covered. However the baby will be uncomfortable in a confined space and will also end up disturbing other people which may not be good movie theater ettiquite. I understand you want to have some some out so have someone watch the baby for you while you enjoy the movie.

No its not advisable to take the baby till the age of 3 yrs. However many parents take along with them . Very small babies can't withstand the loud noise and become cranky