The thing is I am not convinced that early fission nuclear weapons are really an instant "I win button" for either side although I suppose it depends on how many are available and what the delivery systems were.Even if Germany managed to wrangle the USSR in 1941 and force submission of the British around that time they'd need a decade to build a Navy to speak of and would *absolutely* need the element of surprise.
Based on prior German planning the invasion points might be Sandy Hook NJ and a (Salisbury?) beach on the Massachusetts/New Hampshire border with potentially another landing somewhere in the southern US - maybe Wilmington NC or Virginia Beach. Infrastructure farther South at that time will be a problem as will the lack of major highways outside of the Northeast for a mechanized army. Germany had eyed the Hoover Dam before the war and Canaris might use his ties to the AbWehr to try to tip off the Americans via disloyal spies. Assuming he is removed or neutralized, expect massive levels of sabotage. Also expect that by 1947 the US armed forces have not sat entirely idle nor has Canada (which might carry on the fight), they will be taking cues from the Allies elsewhere and likely getting examples of tech from underground movements in Europe. Germany will have late 1st gen/early 2nd gen jets in the skies along with heavy naval firepower but as previously mentioned they need a base of operations nearby (Newfoundland, Cuba, etc.) which will also likely tip off and concern American authorities. Again, unless they bring in lots of nukes and hit several high-level targets at once for shock-and-awe for immediate surrender, I give them four to six months or the invasion fails within eighteen months. At its highwater I would expect most of the coastal northeast to be overrun but no farther west than Pittsburgh nor further south than Richmond if not Baltimore or Philadelphia.