Am I now ready to add 3 female and one male Betta fish into my aquarium?

I'm not sure you have enough room for all those fish. Male bettas do attack females sometimes and it is best not to house them together unless they are breeding. I've heard of people having peaceful betta communities, but only in large tanks like 20 or 30 gallons with lots of plants and driftwood so the females have lots of places to hide if they need it. I think if you put them all in such a small tank your going to have fights on your hands.