I understand that 'BIG' means different to different individuals. Here by 'BIG' I mean life-changing money (bigger than 20x of your monthly income).
1. Let the money sit in your bank account (wallet) for at least one month. It will allow you to settle down your heightened emotions. Just let the amount sit and do not do anything with it for at least one month.
2. Go on a low-cost, week-long vacation with your family and friends (do not tell anybody about your winnings; do not boast) immediately. It will help you make your relationships stronger and will certainly help in doing step 1.
3. Do not change your lifestyle immediately, as it will help you to remain disciplined, which will eventually help you out to earn even more.
4. Consult a certified financial consultant and invest in a diversified portfolio other than gambling, probably for the long term, at least 80% of your winnings.
5. If your winnings are even greater and allow you to quit your job, then use your time to learn finance.
If you have any suggestions feel free to addon.
Gonna add considering to quit gambling for good; you won't win consistently and for me it is worth considering to quit if the amount is decent enough. What's common is that a gambler would be slowly betting the profit aiming to make things bigger however as I've mentioned profit in gambling won't come as we please; it will all depend to our luck and fate. But all of the recommendations above are good options to make. The only thing I doubt all people could do is with 4 and 5, 'coz some people are looking at it as a waste of money rather than viewing its long term benefit. Some people are having desires of having their own business upon getting a huge amount of money but not all people are willing to invest on the learning phase of the journey.
I won't suggest quitting your job as well as long as your time could still accommodate it. No amount of money is enough to cover all your expenses forever. The only factor to consider doing so is if you already have something that will cover your earnings from your job, perhaps a business as what we are talking about.