Re: when i will get Lumia denim update for my nokia lumia 525
On many phones, "Denim" is merely Cyan that has been renamed to match Windows Phone 8.1 Update since Lumia Cyan firmware still functions fine.
Worth noting that it doesn't cause issues. Don't think about Denim, don't lose any sleep about it, just be excited for Windows 10 because not much is happening on the update front for your model. (especially so if you are on the Preview for Developers)