In the BP of the character, I have a stamina recovery chain, I need a delay to be triggered before it is executed, once, and after that, so that it works without it, only with delay. Simply put, if I did some action (running / jumping), stamina should not start increasing immediately, but after some time (1/2/3/etc. sec), if there were no actions wasting it.
So I think the image you’ve sent here is your algorithm for gradually increasing the stamina. I understand like you wanna keep that slow regeneration but want to implement a big delay before that starts, right? So to do that, you can bind those actions you got there to a bool type variable that gets set to true once that big delay before that is complete. You can also use timers for this as well. And even more! There are literally countless ways to achieve this. You can also use a do once node to make sure that doesn’t get triggered again.
Also, you can make this gradually increasing stamina code smoother by using a finterp node instead of delays. Then set the speed for the regeneration. Hope this helps! 
Id recommend using GAS and the attributes system, pretty easy to setup a delay effect like this
