how far in advance should I buy a Swiss travel pass?

Imho, no need to buy the pass in advance.

"is there anything else anyone recommends about Swiss travel for a newbie?"

perhaps check Swiss Railways website - http://www.sbb.ch/en/home.html , maybe you won't need a pass at all. with deals like Supersaver tickets you travel around Switzerland cheaper than with Swiss pass

The question of whether to buy a pass for Switzerland, and which one, is more complex than for most other countries. Ironically, that's because most other passes are bad deals these days (so the answer to "which pass?" is usually "none!"), while passes for Switzerland can still save money and/or hassle.

Once you have an itinerary, you have to start looking at the available deals. Remember that the Half Fare Card is easy: if the total of your known and definite travel adds up to twice the cost of a Half Fare Card, you can't lose. And a Half Fare Card isn't just good for trains, but everything that moves in the whole country - including boats, mountain lifts, and even local city buses! However, you do have to buy tickets every time. With a Swiss Pass, you don't have to buy anything on covered days - just flash your pass. This was a great convenience, and an added value I hadn't anticipated (it's not hard at all to buy tickets, but I did appreciate not having to do it for all but a few things).

Do watch for sales on passes. When I went in September 2014, I was able to get $50 off a Swiss Pass (bought through Rick Steves with free shipping). Again, for my needs it was great, but you have to do the math for your particular trip.

If you want the flexi-style of Swiss Travel Pass, you can order it here and allow about a week for home delivery. You might especially do that if you see a special offer advertised this summer. Special offers are pretty typical for fall but I can't predict when they would be announced. Another reason to have the pass in hand before leaving home could be if you are arriving by train from a neighboring country and want to be able to use the pass from the border crossing.

Note that all Swiss pass products are now pre-validated for a specific travel window (one month in the case of the flexipass, or a specific number of travel days for a consecutive pass). If you want a consecutive-day pass, it is available to print at home. Both types are also sold in Swiss train stations, including Zurich airport.