Tracy suggested you continue PU/PD until the next scheduled feeding but many of us have our own personal cut off point. For myself, I only ever attempted resettling for 20 mins. I know others go for 45 minutes. It's up to you.
You mentioned in your other post that your LO went through the 4 month regression and it's important to bear that in mind when you are helping him resettle. This is a very common phase for babies to go through and the fact of the matter is, he may not be able to sleep for more than 30-45 minutes until he's through the regression.
It would be helpful if you could post your EASY as there may be small tweaks we can see that need to be made that will help your LO sleep better. As I mentioned in your other post, I will be merging the two as they are very similar in nature.