With the hyperdrive out on the Falcon and with Fett pursuing, it wouldn't take Fett long to know Solo's destination and to contact the executor with that info. From that point, using ships with fully-functional hyperdrives, Vader and a garrison of troops could easily secure the planet before the Falcon arrived. Fett only needed to land a good bit away a little bit later and join the Imperial forces at any time before the "dinner party."