You can establish a traditional IRA whether or not you are covered by any other retirement plan. Wages or net earnings from self-employment can serve as the basis for a traditional IRA contribution. Traditional IRA contributions are not limited by annual income.
The SECURE Act of 2019 removed the age limit at which an individual can contribute to a traditional IRA. Prior to 1/1/2020, an individual could not contribute after age 72 (70 ½ if you reach 70 ½ before January 1, 2020). The Act now allows anyone that is working and/or has earned income to contribute to a Traditional IRA regardless of age.
You can contribute up to the lesser of 100% of your earned income or $6,000 for 2019. For 2020, you can contribute up to the lesser of 100% of your earned income or $6,000. Once you reach age 50, contribution limits on IRAs increase by another $1,000. This allows for a "catch-up" contribution for those nearing retirement.
Total annual contributions to your traditional and Roth IRAs combined cannot exceed: 2019: $6,000, 2020: $6,000 (under age 50) 2019: $7,000, 2020: $7,000 (age 50 or older)
You can wait as long as April 15 of the following year (the due date of your individual income tax return) to contribute to a traditional or Roth IRA account.