This is a highly individual process. It depends on your personal circumstances. Some folks adjust relatively fast; others need much more time and effort to feel any sort of balance. The important thing is for you to take your time, gather as much information as you can comfortably absorb, and then permit yourself the necessary space in which to process it . Real truth has nothing to fear from rigorous examination; feel free to examine the facts at a comfortable pace for YOU. Some people feel such a sense of urgency and dread when they first glimpse the 'man behind the curtain' that they leap into the first replacement 'salvation package' offered. Knowledge is power; how much knowledge will you need to make an informed decision about your future? Unfortunately, no one but you can figure that out.
I was in turmoil, lost, unsettled, while I was IN the organization. I was always comfortable with my decision to leave, because I KNEW there was something irrevocably wrong about the Society, although I hadn't seen all the proof yet. (I must say though that seeing my suspicions and conclusions validated online did give me a sense of satisfied closure.)
I can't help you with the happiness question; that seems to me to be partly temperament, partly circumstance. If you are determined to live a happy balanced life, and you're willing to learn new ways to do that, you stand a good chance of making fast progress. If you have a lot of emotional baggage, don't expect deculting to make that burden any easier to tote. Those raised in it from early childhood often have the hardest time learning what true balance and happiness are. I found it was hard to separate the cult from the family dysfunction; the problems often overlap.
As has been said before, finding a support system and a social routine outside the JW congregation is very helpful. The more well-rounded your activities, the faster you will feel a part of your community. Isolation is depressing unless you genuinely choose a solitary existence.
Professional counseling can be useful in sorting out any tangles you may discover while sorting out your ethical issues. Sometimes a neutral sounding board is needed to help you step back and view a situation more objectively. Here, too, you should feel free to examine any therapist's offerings and choose what works for you.
If you're looking for a comfortable replacement 'salvation package' to plug into the empty socket left behind after you wrench the Tower out of your heart, I can't help you. Real life doesn't come with guarantees.
Not all of us who have left the Tower are happy or comfortable. We are, however, free to decide for ourselves how to pursue comfort and happiness. Personal responsibility is an awesome thing. Happiness finds me incidentally in this journey through life, and I embrace it when it visits. The rest of the time, I try to laugh at the absurdities as I bumble along the roads less travellled. It makes the inevitable slogging easier to bear.