Assuming that you have taxable compensation to make an IRA contribution, whether if is deductible or not depends on your MAGI for ANY contribution. and if you are covered by a retirement plan at work.
The maximum IRA contributions for 2019 & 2020 is $6,000, or $7,000 if you’re age 50 or older by the end of the year; or your taxable compensation for the year which ever is less.
(Taxable compensation is generally wages that you worked for - W-2 or net self-employed income minus the deducible part of the SE tax, but can include commissions, certain alimony and separate maintenance, and nontaxable combat pay ).
See IRS Pub 590A "What is compensation" for details:
See this IRS link for Traditional IRA deduction limits when covered by a retirement plan at work.
No roll over. First time opening an IRA. Another question: Is there a specific length of time to keep the contribution to take the deduction?
Do you mean, must it stay in the IRA for a time period? No, but the "deduction" is actually a tax deferral, not a tax forgiveness, so when you take a distribution from a Traditional IRA you must then pay the tax that was deferred plus a 10% additional penalty if distributed before age 59 1/2. The advantage of a Traditional IRA is long term investment for retirement and growth since the tax is in the IRA and can grow along with the principal. Hopefully when you retire you will be in a lower tax bracket so deducting now and paying the tax later can be an advantage.