Apartments in the same line are identical, so nothing you post is anonymous
Leaving the address out of a caption anonymizes a house in the suburbs. It does not anonymize an apartment.
Everyone in the same line has the same layout, the same window placement and often the same original tile. One photograph of a finished bathroom identifies the unit to anybody in the building, and usually to the managing agent as well.
Permission therefore has two owners. The shareholder or unit owner has to agree, and the building may have something to say about photography, signage and advertising in common space. The alteration agreement is generally where that gets settled.
Timing matters more here than the asking does. A request that goes in alongside the alteration agreement is one line in a document a board is already reviewing. The same request in month three is a new item somebody has to raise at a meeting, and the easy answer at a meeting is no.
Accept that some jobs are simply unpublishable. An owner in a strict building can be delighted with the work and unwilling to be identified anywhere, and pushing on it costs you the referral that job was going to produce.