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: Cascadian Dark Ale #2: Empty
Secondary #1: Berry Rhubarb Wine #2: Empty #3: Empty #4: Empty
Kegged: Irish Red
Bottles: Surly Bender clone, Big 50 Barleywine, Framboise Lambic, Dark Belgian Strong, Kicked by a Moose Scotch Ale, Russian Imperial Stout, Sparkling Elderflower Wine, Barolo Wine, Peach Rhubarb Wne
On Deck: Spruced Winter Warmer