Because the partnership has a fiscal year ending on January 31, the Schedule K-1 showing the partnership income is reportable on your 2018 tax return. You'll also pay taxes on your 2018 W-2 income, so your overall income may be somewhat elevated for 2018 compared to years before and after 2018, but you won't be paying taxes on the same income twice (although some of the income might be taxed in a higher tax bracket than it would be if your income had been spread out more uniformly across taxable years).
(Keep in mind that your tax liability was lower than usual when you began participation in the partnership, so the shifting of income that results from the partnership's January 31 fiscal year somewhat cancels out between your beginning and ending of participation.)
If your new employer offers a 401(k) or similar qualified plan, you might consider making elective deferrals to reduce your 2018 taxable income. If you are eligible for a deductible IRA contribution (which might not be the case with the elevated income in 2018 if you participate in an employer-provided plan), you can also contribute to a traditional IRA to reduce your 2018 taxable income. By making these retirement contributions, you are deferring the income to later years when you receive distributions from these accounts, but you'll need to wait until you are age 59½ to make distributions, otherwise you'll likely owe a 10% early-distribution penalty.
