Either
>>95863765 (OP) (but this assumes the module in question is playable, and this is not guaranteed) or the good old core concept by reduction.
You know, those tasks they gave you back in late elementary, where you had to write skeleton of something, consisting of set of points, and then merely expand on them.
So in this case: prep 3-5 scenes for today's game, write them down and unironically think really hard about them playing out and how you can interconnect them, but don't actually plan details, just make sure you understand how they connect.
Example
Let's say it's a CoC game and the basic premise is that the party is running a hotel in New England seaside
1) A single tourist arrives - a secretive young student - and he will be found dead soon after
2) A nosey journo arrives some time after, since dead body in a dead-beat town
3) Blatantly obvious cult representative also shows up, claiming to be fiance, either to the hotel (if body was disposed) or funeral (if it was reported to the police), asking for a book he was carrying
4) Night-time showing of a ghoul, tearing apart the garden next to the hotel
You now have 4 elements you want to include during today's game. You fluff them up on your own (adding characters, preparing sheets for them and the likes), you know what you want to happen to day and thus what pace of running you want and you more or less know the schedule.
What your players will do is up to them, but you know what you want to happen and how it connects all together. What are motivations of your NPCs? That's up to you, but it can also react to the players actions in a fluid way.
Trying to make it all detailed plan is a surest way to either end up with a railroad or, worse, stumbling when something outside of your narrowminded plan happens