Do I need to pay estimated taxes quarterly if I make enough trading stocks?

I have a full time job and have started trading stocks few months back. Already I have enough realized gains that will force me to pay additional tax. My question is do I need to pay estimated taxes quarterly based on the profits I have made so far or can I wait till the end of the year to pay my taxes.
Any one who has been in this situation, if you can share your experience, it will be greatly appreciated.

What taxes do I have to pay if I am a Freelancer in India?

Seeking for some good advice 🙂
I am a self-employed solo web-designer.
I was actually asking “what taxes” do I have to pay? Not “whether” I need to pay taxes… I know and it’s my duty to pay taxes. Just don’t know what taxes and whether I need to pay anything extra for solo proprietorship.

Some answers were really helpful. Thank you!

Can somebody suggest me a good book on Financial Planning & Taxes?

I am an insurance agent and mutual fund distributor. I am a science graduate, and hence know least about concepts of commerce.

I am looking for a book which can help me offer better financial planning to my clients. The books should explain the concepts of various investment instruments like Mutual Funds, Stocks, Real Estate etc. It will be great if the books contains chapters on Taxes (and its various sections). In a nutshell, a book for dummies on Financial planning and Taxes.

Please suggest. Thanks a ton.