Tricky to answer this as what you call ‘fresh’ may be ‘reasonably well rotted’ to others. If it is recently cleared from stables, with horse poo and bedding all recognisable, I would stack it until autumn. Also it could enrich and help your compost ingredients to break down if you add a couple of forkfuls every week in the summer.
I would apply fresh manure to beds only as part of a long term clearance of perennial weeds and with a light excluding mulch on top, preferably black polythene, and for a whole season. Like having a composting, ground clearing and enriching programme all at the same time. Courgettes and squashes could be planted through small holes in the plastic, possibly potatoes too.
The reason for using composted/stacked/decomposed/well rotted (pick your words) manure is that it behaves mostly like soil and can be sown or planted into. If too fresh, its own decomposition process takes nutrients from growing plants. Also the unbroken-down lumps get in the way of sowings and small plants, and may offer sanctuary for slugs.