I think it would have to be a harder line response to the invasion of Bohemia, that wasn't war. But one that makes Germany turn its sights west before heading back east, and one where Germany is reasonable confident there won't be a Polish or Soviet Union through Poland attack. Or one they are confident of fending off.
Hiding Germany is preparing for War in the west is a bit hard, so both sides are going to be mobilised. Germany performance in the west was already quite high OTL, so not sure where any improvements would come. Britain might only have a token BEF in France, so even that getting pocketed won't do much else, and the Wallies have a year less of war preparation. Germany not changing its invasion plans, not having the Polish experience and doing it in 1939 meanwhile could make it costlier or take longer.
The Soviet Union might kick up its expansion a year earlier, taking the Baltic states and attempting to browbeat Finland. Poland would know they are next, but the speed of France falling might shock them into complying with German demands to stave off demands. Poland is generally in a terrible situation, as the USSR has claims on their eastern territories and Germany isn't at all friendly. So ceding Danzig and corridor rights, along with economic subjugation to avoid a full on invasion. Perhaps this is enough for Hitler to focus against the Soviets, thought it won't be as much of a surprise thought it could start much further east. But against the prepared Soviet lines, instead of half built ones.