You'll hear different recommendations from different sources. Most breastfeeding sources (like LLL, and a lot of LC's) will recommend waiting anywhere from 4-6 weeks before introducing a bottle or a paci to avoid "nipple confusion". However, it really depends on the baby - some have absolutely no trouble with all of them no matter WHAT age they're started. What seems to make the most sense to me is to wait until the latch is firmly established first (no soreness whatsoever, good weight gain, enough wet and dirty diapers) before starting either.
That said, if you're noticing changes in the latch, then your lo is one of the babies who has a harder time switching.
To help, you can make sure to use a paci that looks as much like your nipple as possible (I personally liked the Avent ones). Also, when latching your baby to nurse, be diligent - as soon as the latch changes or shifts, you'll have to break it off and re-latch. If you leave it be, your baby will learn to have the poor latch. The last thing you could try is remove the paci altogether and try again in a week or so - should remove the latch problem completely after a few days. The down side of this is that your lo may never take it again, and you may have a rough few weeks having to use other soothing methods. It's really your choice what you think might work best for you, though!
Hope that answers your questions!
