they ought to know what to do. but don't let anyone talk you into believing that a new car needs a polish... that's just hog wash.
i see that your garage is only partially enclosed, so i would recommend going down the synthetic route with a sealant, for longer lasting protection. carnauba waxes generally give a deeper glossier shine than synthetics, but the trade off is that they aren't as durable and get washed away after abt 4 washes/showers/storms.
plenty of choices of sealants out there, i personally prefer Meguair's...you can check out my car during the meet ups.
for a white car like yours, i suggest you detail once every month/2 months if possible or you're gonna end up with a yellowed car after a few years. in fact, if you have the time, i say apply a layer of carnauba wax over the sealant for best results between your detailing session.
In summary, here's what i'd do for the exterior bodywork if i had a brand new alpine white M3
once a month (done by professional detailers):
1. wash
2. clay bar
3. sealant aka synthetic wax
once every 2 weeks (either DIY, train the maid or by professionals):
1. carnauba wax, liquid kind is easier and quicker to apply
once a week or whenever car gets dirty (DIY, maid):
1. wash
2. spray on wax
for best results, cleaners should be used to remove the previous layer of sealant before re-applying the new layer. but this varies as some products already contain cleaners that help strip off the old layer. a competent shop will know what's in their detailing products so leave it up to them to worry abt stuff like this, but its good to just be aware anyway.
you'll probably need a polish somewhere down the road, but not so soon. and you probably won't need it too often as well because with white, the emphasis should be on PROTECTING and maintaining the paintwork to prevent yellowing.
IMHO, no real point going through the pain of a thorough wash, clay, clean/polish, sealant, wax regime since there won't be an appreciable difference on a white or light coloured car... law of diminishing returns. save your money: focus on paint protection.
hope this helps. happy detailing and feel free to PM me if you need anything.