Generally, good planning prevents having to have something go out the door in the next two hours. If you can't plan well, just be courteous, but firm and tell your customer a few hours of waiting will be necessary.
If you're any good, you can apply them right away with small yard
signs, regardless of how much coverage or softness occurs after printing. Something that small is almost impossible to mess up from lack of waiting.
We just did 15pcs 4' x 8' prints on Wednesday which were started printing in the morning and finished by late afternoon. Printing started at 8am and by 4pm they were all put down on 3/4" duraply [
MDO] with a Big Squeegee with only one little mishap and that's because we pushed too far.... too fast and had some wrinkles which came out after a few minutes of playing with it. The applying the prints took 45 minutes. The last few only had maybe 30 minutes of drying. Almost right off the printer onto the board. We had painted all 15 boards the day before. Dried over night.