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: Umlaut my Kölsch VII #2: Empty
Secondary #1: Empty #2: Empty #3: Cab MerMarqeNac Wine
Kegged: Mugged a Monk Paters
Bottles: Dark Belgian Strong, Black Raspberry Rhubarb wine, RIS, Carmel Apple Cider, Big 50 Barleywine, Framboise Lambic, Barolo Wine, Berry Rhubarb Wine, Black Currant wine
On Deck: BGSA