Again, this is only my speculation, and I certainly can't find concrete evidence for it, but....I suspect that the reason for this long delay is because there actually wasn't such a delay. In other words, Stephany died long after Joran left the hotel, which left those responsible scrambling to find a reason for why so much time elapsed before the room was checked.
The most logical guess I can make is that Stephany was supposed to be involved in the "sting" or trap, or whatever it was that had been planned for Joran. She felt remorse, gave him a head's up, after which he left and it took a few days until her betrayal was discovered. That's why the uncut video from that security camera would be crucial evidence, to determine exactly what activity, if any, occurred in Joran's room after he left. Of course, any entrance or exit from his room necessarily proves him innocent.
Btw, there is a better translation out there (sorry, no link- it's from a site WS doesn't want linked to) of the Dutch article from yesterday, regarding the security camera. It is now clear that these reporters claim to have actually visited the hotel, and maintain that there was no camera outside room 309 prior to Joran being there, and it has been removed since the murder. Now, it may be that the authorities confiscated the camera for their investigation. However, if these reporters have some kind of evidence (testimony of long time hotel staff, perhaps?) that a camera was only installed at this spot after Joran rented that room, then I think it's pretty clear evidence that he was being monitored by somebody, for some purpose.