Waiting Period for Fir, and Sikkens stain

I just had a contractor replace the planking on a mid-sized deck with fir lumber. After reading through this site I realized that i knew next to nothing about how to properly stain a deck. Before I think about what the proper stain is for this deck, my first question is how long to wait before staining. In the main article on this site the advice is "weather 1-12 months, depending on stain brand." 1-12 months is a huge range, and I'd like to stain the deck ASAP. So, my first question is, is there any particular waiting period that's appropriate for fir?

The second part of this question involves the choice of stain. Since we didn't need to replace the existing railings, my inclination was to use the stain that is on the railings, to match color. That stain is Sikkens 045 Mahogany. However, after reading the reviews of Sikkens on this site, I'm seriously reconsidering. Hate to have to go through the cost and hassle of stripping the old stain, but that seems to be the advice when I read about Sikkens here. If anyone can rehabilitate that stain for me, would be nice 🙂