Welcome! With that kind of growth I can see why you stopped shaving. It must have been a real chore! That's a very nice beard for only three weeks. You certainly appear to have what it takes to grow the long, braided beard you seek.

If you're planning to wear a long beard then, yes, there will come a time where shaving your neck will become unnecessary as no one, not even you, will ever see it. In the meantime though it's a good idea to maintain a line there to keep your beard looking neat and deliberate.

It's a good idea to start using an oil daily. It will help your beard stay healthy and keep your skin healthy too. Just put a few drops in every day, massage it into your beard and the skin beneath, then brush or comb it through.

Also, if you're planning for a big beard I encourage you to consider training rather than trimming your mustache. Just follow the instructions in the 'Taming the Wild Mustache' thread in my signature. Big beards tend to look best with bigger mustaches. Your mustache will be very annoying for a while but, in time, it will lay to the sides and behave itself.

Be sure to post updates here regularly for feedback and encouragement!

Cheers!
Tom


Some helpful links:
Library Central of Beard Growing


Taming the Wild Mustache
Tips for eating and drinking with a big mustache

Excess on occasion is exhilarating. It prevents moderation from acquiring the deadening effect of a habit. ~ W. Somerset Maugham
A jerk with a beard is just a bearded jerk, but a bearded gentleman is awesomeness personified. ~ Triibeard