There is an application for US and WO and I have prior art for it before the date of its priority date, but I do not know if it will be considered prior art as I suspect there should be time restrictions for it to apply. Which are these?
It is prior art if the event that disclosed it (or the equivalent of disclosing it under the law) was the day before. Except in the U.S. if the inventors/applicants were the ones who made the disclosure; then there is a complicated 1 year grace period. To be prior art in establishing obviousness it also needs to be in an analogous art or otherwise pertinent to the problem being solved. There is also "admitted prior art" which is something, not by the inventors, that the inventors say is prior art even if it would not otherwise qualify.
Don't say the words "prior art" loosely or in a patent application.
In Europe there is a difference between prior art used to break novelty and prior art used in an analysis of inventive step (like obviousness). An earlier filing, even if not yet published, breaks novelty. But to be used in an inventive step it wust actually be public the day before the filing.