The first year you don't need to pay estimates as long as you pay in (by withholding) as much as your tax was last year. But if you will have a big income you should send in estimates so you don't owe too much next April on your tax return.
Estimates are optional to pay. For SE self employment tax - if you have a net profit (after expenses) of $400 or more you will pay 15.3% SE Tax on 92.35% of your net profit in addition to your regular income tax on it. So if you have other income like W2 income your extra business income might put you into a higher tax bracket.
Here is the blank 1040ES and Instructions
<a rel="nofollow" target="_blank" href="
https://www.irs.gov/pub/irs-pdf/f1040es.pdf">https://www.irs.gov/pub/irs-pdf/f1040es.pdf</a>
