His last-minute dealing with the Russians and the vast concessions he made to ensure a passive east so he could turn west makes me think he knew this was likely the moment his bluff would be called.
Internal documents and strategy show that
after 24 August 1939 German leadership was uninterested in a peaceful solution to Danzig, at least in regard to dealing with Poland specifically. If Hitler expected that France and UK would not honor their guarantee to Poland, he would not have felt the need to make a Pact with the Soviet Union. I agree with you that by August '39, Hitler knew that the British and French probably would come to the aid of Poland. If Poland caved in to German demands after 24 Aug, the date on which the M-R Pact was announced, it would've been extremely awkward to cancel and rewrite the Molotov-Ribbentrop pact. In the week before 01 Sep, Hitler had already decided that war was imminent the diplomatic maneuvering at this point was merely smoke and mirrors for the purpose of deflecting some of the blame from Germany for starting a second world war.
I don't like how Paradox chooses to do the 'Danzig or War' decision. Historically Germany presented their demands to Poland for Danzig in early '39, Poland essentially rejected these demands in April 1939. The decision to give up Danzig was no longer valid for Poland after the M-R Pact was signed.
1944 was an ideal date. I think he was prepared enough to take the risk.
What do you think 1944 was an ideal date for? At the start of 1939, Germany had successfully wrong-footed the Allies in regards to mobilization. After the partition of Czechoslovakia, the Allies belatedly restart their rearmament in earnest. At this point Germany begins to fall behind in relative strength to UK-France, therefore Hitler cancels the absurdly unrealistic Z-Plan for the navy and prepares for imminent war. If Germany is obsessed with using it's military to satisfy it's revaunchism, 1939 stands out as the ideal date to start a war.
If Germany waits until 1944 to start a war, they will have fallen far behind the Allies militarily since German would be essentially been closed off from the world economy concentrating on building massive fleets of ships and planes. Germany at peace would struggle to maintain this massive military and have no hope of keeping it upgraded. An analogy would be that of North Korea and South Korea. North Korea has a much larger focus on military production but it's actually much weaker than South Korea militarily because it's been focusing so much of it's energy for years on maintaining a ridiculously large army.