A noticeable delay after selecting drive or reverse is called delayed engagement. Depending on the transmission, possible causes include fluid-level concerns, hydraulic leakage, control problems, or internal wear.
Note whether the delay occurs after sitting overnight, only when warm, or in one direction. These details are more useful than repeatedly shifting back and forth to test the problem.
Contact Certified Transmission in Council Bluffs, IA for an evaluation. Do not raise engine speed to force engagement because the vehicle may move suddenly when the transmission applies.