shRNA transfection itself gives transient gene knockdown. shRNA mediated knockdown is normally more stable and longer than siRNA's which provide efficient silencing for up to a few days.However, you can integrate the shRNA sequence into a plasmid vector which in turn can integrate into the cell genome thereby providing stable long-term effects.

You usually have 48-36 hours of k.o. or k.d. after transfection, you can use Cas9 plasmid with the lentiviral delivery system to get stable k.o. or overexpression of your targets. If the process of vectors design and application is not well established in your lab. I suggest you contact Millipore Sigma or Thermofisher for initial constructs to establish the workflow. Then you can increase the complexity and design your own.