WFI Instruction

Hi,

I want to use the wfi instruction in my code. I'm sending a command to a module and wait for the reply.

I have configured UART communication with the module. Will it be good to use wfi() instruction? I know that it will turn  the cpu to power down mode.

Instead I can use some arbitrary delay, but the time taken for the reply is varying in nature.(.7 to 2 sec)

What if I poll the Interrupt flag? is there any alternate solution ?

Thank You.