My G.pulchra spiderling molted a week after it stopped eating, and my A.geniculata stopped eating when its abdomen turned black and waited at least 10 days beofre it molted. Be patient, blondi's are nutorious for fasting for a long time before molting. I'd expect it to happen within a month for sure, probabaly a couple of weeks. Don't feed it or anything, and make sure all food is out of the cage but make sure a full clean waterdish is always available.
I'm not entirely sure. I think it largely depends on the size of your blondi. After my blondi's first molt (2" before moult), it's abdomen was black for almost exactly a week before it molted. The second time I saw it molt, it's abdomen was black for not quite two weeks (a week and five days, approximately).