I agree it's desirable to give timbers some protection during transport and raising. The #1 criteria I look for in a finish material is ease of touch-up, so that spots that are dirtied, chipped, or stained can be addressed without redoing entire surfaces. I avoid products that form a surface film [such as polyurethanes] because when damage or deterioration occurs, often all traces of the old finish have to be removed because new doesn't blend well with old. I've used primarily penetrating oil finishes, you'll find products made by a number of manufacturers. Low-toxicity products using citrus oil solvents are available. Products containing linseed oil may provide food for mildew organisms. Application can be by saturated rag [wear rubber gloves], roller, brush, spray, etc.

I've avoided using wood stains because, when inevitably you've got to make a repair, it's near impossible to get a good color match. Repairs to natural wood may not blend initially because hue changes with age and UV exposure, but with a little time, most repairs will blend in well.

I've also used Anchor Seal on end grain with excellent results.