Well, I'd give it a week just to ensure all the hens have had a turn with the new rooster.
Something else in your post leads me to believe you think your hens will hatch and raise chicks. Just naturally.
This is one of the biggest misconceptions held by folks new to chickens: all hens will hatch chicks if you just don't take their eggs away. NOT TRUE.
And, unfortunately, particularly true with regard to RIRs. It's not a "broody" breed, as a general rule. (I know of a couple BYCers who have had A - yes, single - RIR go broody, each.)
Y'see, most hatchery chicks come from production birds, that is, birds with "broodiness" bred out of them so there is no down time due to a hen wanting to hatch eggs instead of just lay them.
Multitudes of BYCers have had flocks in which NO hen ever went broody, even those breeds more reputed to be inclined towards broodiness.
If so, you'll have to add a few more hens from breeds more commonly found to be broody. Check out Henderson's Handy Dandy Chicken Chart at
http://www.ithaca.edu/staff/jhenderson/chooks/chooks.html
Or hatch the fertile eggs artificially, through the use of an incubator.