The fermentation is created by the salt and enzymes in the cukes. Its a LACTIC acid type fermentation. The vinegar added will simply slow or stop its natural way or fermenting. Covering the jars with a plastic canning lid helps to reduce any mold on the surface, as well as allow a bit of venting of fermenting gasses. Usually its not really much mold, but a whitish scum. I don't allow that much time at room temps for fermentation. If I wanted a fully fermented cuke, I would only give it about 10 days to two weeks, and then add a bit of vinegar and place in the fridge. The cukes I use are very fresh picklers and are washed off and the ends trimmed off prior to packing into jars. I think the reason I never see mold is because I only allow 2-3 days of partial fermentation and then add the small amount of vinegar and place in the fridge. I also prefer to use a Mrs. Wages dill pickle mix with added fresh dill weed and fresh dill seed heads. The mix contains stuff that prevents mold from forming. I was lucky last year as my cukes matured in time while the dill was just going to seeds. This year with temps below 70 degrees even in all of June and now July, the cukes are still tiny plants and the dill has now started to lose its fern leaves.

I haven't used the BBB fermented recipe, but it's not unusual to see a SMALL amount of vinegar to reduce the likelihood of mold. In other words it sanitizes.

A little vinegar won't appreciably slow fermentation. I hope you're skimming regularly. Most of the "white stuff" is yeast, but if you're seeing what's clearly mold, that's not such good news. If the cukes still smell nice and fresh and are clearly turning into pickles, then all you need to do is skim carefully and make sure your container is covered. It wouldn't hurt, either, if you see mold recurring, to add a bit more vinegar. Slowing fermentation is an inconvenience. Rotten cucumbers is a shame.

I hope the area where you're keeping the pickles is not too warm. The rate at which fermentation progresses is very much determined by temperature and differences in individual environment. There's no hard-and-fast rule.

If the cukes are turning translucent, they're just about ready, regardless of how long or short a time it's been.

Carol