Workforce Training Enhancement Act of 2017 This bill amends the Trade Act of 1974, with respect to trade adjustment assistance (TAA) for training to adversely affected workers, to authorize a state to use certain funds distributed by the Department of Labor to reimburse the costs of providing training to an adversely affected worker before the worker is approved for training under the Act if those costs have been paid by: the state from state funds, the state or local workforce development areas within the state from funds available for workforce investment activities and providers under the Workforce Innovation and Opportunity Act, or another entity eligible in the state under the national dislocated worker grants program from funds available for that program. The use of funds under this Act shall be conditioned, however, on the worker's coverage by a certification for TAA eligibility for training meeting approval requirements which commenced after the date on which the total or partial separations of the group of workers covered by the certification for eligibility began or threatened to begin.