For a big fat RIS, I like to bulk age for 4-6 months. Longer if you can stand it. They aren't going to be great until 9-12 months anyway so if you have the carboy space that is where I would do it. You may also get a more consistent batch this way vs bottles.
The only concern with a long bulk age in secondary is oxidation. I like to put a CO2 blanket on top (from my kegging setup) and then seal it up good with an airlock. Just have to remember to top up the airlock every month or two.
Primary #1:Dunkel #2:Empty
Secondary #1: Peach Rhubarb Wine #2: Empty #3: Empty #4: Sparkling Elderflower Wine
Kegged: Piker Liker Porter, Umlaut my Kölsch V
Bottles: Big 50 Barleywine, Framboise Lambic, Red Rye IPA, Dark Belgian Strong, Belgian Golden Strong, Kicked by a Moose Scotch Ale, Apfelwein, Russian Imperial Stout, Carmelite Tripel, Rhubarb Wine, Barolo Wine
On Deck: Irish Red, Surly Bender clone, Spruced Warmer, CDA