I know you're asking J Francho his thoughts on this, so I will simply read what it says on bottle "allow first application to dry completely before use. Treating the night before is recommended". "Reapply while fishing as necessary no drying time needed after first application". I have never used it during a fishing trip ever so for me its always been the night before fishing. I also hit them all before I put them away for winter as with wood heat the humidity is low and it keeps the line from drying out indoors for the winter. 

I spray some on when I spool a reel and rarely have to reapply.  

1 hour ago, pauldconyers said:

Couldn't those conditions be satisfied by doing it prior to a trip too?

If there's time to let it dry completely.  It works best that way.