Establish each baby's individual feeding rhythm: The general is advice is to start by feeding each baby separately on cue to ensure you establish a good latch and position with each baby. (charlottekeating.com)
Feeding rhythm varies from baby to baby, and you should find your own. (checkpregnancy.com)
However, once breastfeeding has been established, and both mom and baby are in a good feeding rhythm, then it is perfectly acceptable to introduce the bottle or alternative feeding method. (justbreastfeeding.com)