On a "brand new" engine like this, I would dump the oil after a couple of hours run time (that was once the Briggs standard) and change the oil filter too. After that, oil and filter at intervals no greater than 50 hours, or once annually if you use it less than 50 hours per annum. If you have an "off season" lay up period, change your oil just before the lay up begins. That way you have clean, fresh oil coating the innards instead of tired old acidy thin oil. (I never have understood people who wait til spring to change oil that was already "worn out & contaminated" last Fall.
Briggs says adjust your valves annually. That's pretty good advice and it can't hurt, if you are doing a proper "Briggs valve adjustment". If you are not doing it properly, you might just be doing harm 'stead of good.
I recommend adding a bit of Marvel Mystery Oil to the fuel supply (if Cali will let you). The Marvel Mystery Oil in this case serves as "upper cylinder lube" and the main target I am aiming for is the portion of the intake valves that is exposed to the induction draft entering the combustion chamber. The gasoline (and alcohol) in the induction stream washes away the trace amount of engine lube oil that finds its way into the valve guide. Then the fuel and alcohol evaporate to leave a thin film of varnish-like substance that builds up where the valve stem meets the valve guide. The harm of allowing this to occur is that sooner or later, the engine is going to be stopped with an intake valve open...........and it will become stuck open. Next time the engine is cranked, the valve can remain stuck open while the camshaft rolls away normally, allowing the pushrod to fall out of the cup on the rocker arm. The pushrod hardly ever makes a clean escape and usually gets caught on the edge of the cup. When the cam lobe comes back around again to open the valve.....crunch time! The damage might just be a bent pushrod (if you get lucky) but somtimes breaks rocker arms too.
The MMM helps protect against this by keeping a thin film of oil on what would otherwise become a dry and sticky valve stem, and it keeps the valve from becoming stuck.

Mownie,

Yup MMO is still avalable here at Walmart, shame that the container no longer has those great 'testimonials' it once had in the 1960's. Hope I can get a new filter at Napa Auto or such and I was thinking 3-5 hours was a good starting point, flush out any crud may have been left behind in assembly and give it a chance.

As a old VW owner I know all too well the importance of keeping the valves adjusted or Kaboom # 3 would drop a valve and destroy everything (put myself through college repairing VW engines).

I am sure the air quality control board would have a fit with me adding a ounce or two of MMO to a tankfull but what they don't know... can't bother them.

As an old VW owner myself (I mean I had one way back when) I too can relate to the regular valve adjustments requirement. But you might be surprized to learn that the need for periodic valve adjustments on your new B&S is more about keeping the compression release working in peak form so the starter can actually spin the engine to cranking speed than keeping the engine from swallowing a valve.
As to finding an aftermarket oil filter, use the search function of this forum to dredge up some threads that cover cross reffing to some less expensive but equal or better quality compared to the Briggs branded oil filter. There are at least 3 threads devoted to the subject.
But let's be practical here too. I would rather use a Briggs branded filter on the engine until the warranty expires, because if by chance you must (heaven forbid) make a warranty claim, it's so much simpler to present the machine to the "powers that be" with it wearing a Briggs branded filter (and have the receipt where you bought that Briggs filter lest they say you never changed it) than to have to defend my right to use a different brand filter.
Heck, if you got the green to buy this Ariens new, surely you can bite the bullet on the cost of a Briggs filter until the warranty no longer applies.

"if you got the green you can by briggs filters" IMO you can also change the oil more frequently also!!..

I have to chime in here on the 50 hour oil change. Unless they have changed the guidelines that would be under "normal conditions" Rarely does lawn equipment operate under "normal conditions" throughout the mowing season. It's either extremely hot or extremely dusty some time during the season.

IF so depending on where your located in the USA You might consider changing you oil using the Extreme change schedule (dirty or dusty conditions, or heavy loads or extreme ambient temperatures cnoditions)? which basiclly means CHANGE IT MORE often than 50 intervals?! IMO I have never used my equipment in normal conditions throughout the mowing season in my area.

Engine failures IMO are direct link to NOT changing oil enough and running the engine low on oil. I sure you know this being a VW mechanic. I just don't like leaving oil in for 50 hours on an air cooled engine, if you do your asking for trouble down the long road IMO.