You can wait til the end of the year.
You should make estimated tax payments for the current tax year if both of the following apply:
- 1. You expect to owe at least $1,000 in tax for the current tax year, after subtracting your withholding and credits.
- 2. You expect your withholding and credits to be less than the smaller of: 90% of the tax to be shown on your current year’s tax return, or 100% of the tax shown on your prior year’s tax return**. (Your prior year tax return must cover all 12 months.)
If your goal is only to avoid the underpayment
penalty, then paying 100% of the prior year tax liability is the “safe haven”. So, even if you make a third quarter payment, it doesn't have to be for the full amount. Increasing your withholding at work is a better option.
I assume you are aware of the home sale exclusion rules. if not, here are some references:
http://www.bankrate.com/finance/taxes/capital-gains-and-your-home-sale-1.aspx
No changes under new tax law ( https://www.marketwatch.com/story/10-things-you-need-to-know-about-the-new-tax-law-2017-12-20?mg=pro...)
** If your adjusted gross income (AGI) for 2018 was more than $150,000 ($75,000 if your filing status for 2019 is married filing separately), you would need to pay in at least 110% of your 2018 tax under the General Rule to avoid an underpayment penalty.
