Can I wait 24 hours after thawing frozen salmon to cook it?

Yes, you should be fine. However, the freshness of the salmon before freezing should be taken into consideration. If it was already old, you probably shouldn't eat it after four days of thaw. But if it was fresh and then quickly frozen, you most likely won't have any problems. Just make sure it's fully wrapped while thawing, set it on a plate so moisture won't drip into the refrigerator, and smell it before cooking. It will have a little "fishy" smell but it shouldn't stink.