Put a Festival Landlords Finest on a Wednesday, went on holiday for two weeks on the Saturday, came home and added the hops the next Monday I came back, then couldn't bottle until Friday, so that was getting on for four weeks.
No issues. Lots of yeast dropped out so nice and clear when bottling. A month should be fine. I've heard of stuff left longer than that and still be fine but the longer you leave it the higher the risk of infection I guess, although hops and alcohol are excellent preservatives hence the idea behind IPA in the 19th Century!!!
There's something to be said for patience in brewing! And forget kit instruction timescales - they're way too short a timescale for good beer. I think it likes to sit on the trub a while?