this is a question that can be answered with your own gardener instincts. I have well draining soil. I just used my fish seaweed emulsion in August with a watering can. Also i used it in the spray two weeks later. It worked great.

I water really well before I use liquid fertilizers but not after. I only water after I put down dry fertilizers to get it to dissolve some.

I also do not water afterwards after applying LIquid fertilizers...
But like Seil I make sure the soil is moist before applying.
Here in our cooler climate with clay soil I actually water the day before applying liquid fertilizer...

I'm with seil and jim1961: water plants very well before fertilizing (and before fungicide application, for that matter).