I don’t know how it works in your market, but around here when a dj can’t work for whatever reason, they bring in their own replacement. The owner has little to do with it, beyond throwing a hissy-fit if the replacement screws up anything.
If it works anything like that in your area, then be careful approaching the owner. If what he is doing works, he won’t be looking to make a change, and the current dj will get the impression you are trying to do an end-run around him – not making you his first choice should he need a night off for anything. A better approach would be to get friendly with the current guy so that he knows you and feels comfortable with the idea of slotting you in should he need someone.
In the meantime, as you are building that relationship work the hell out of the place you are at currently. Build up a loyal following and make sure they know how to reach you and know where your shows are (here is where the whole social media/marketing thing kicks in to overdrive). When you eventually get the call to fill in, you’ll be bringing some of your followers with you (and encourage them to go around talking about how awesome the dj is tonight), and the owner can see you rock the place. Then he can decide if it made a difference to his bottom line and a change is in order.
Also, I’m not sure what you meant by “but as it being theres no EDM at all, just top 40 Giving him a mix wont do,” but if you want to work at a top 40 place, you should be able to mix it – so no reason not to be able to make a whole demo of it.
Anyway, that’s my advice – it worked for me when I was first starting out. Good luck!
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