In English, if a person states, "a certain event will occur by a" particular "period of time" then does that mean that said event will occur any time within said "period of time" or does it mean that the even will occur the very instant that said "period of time" starts?
Let me elaborate,
If someone says, a construction company states that they promise to complete building the house by August, 2021 then does that mean that if the construction company still completes the house by 31-August-2021 at 23:59:59... then they have still kept their promise?
Or does it mean that the construction company will have to complete it by 30-July-2021 at 23:59:59... in order to keep the promise?