You paid for them, set them all.
Unless you have a local buyer for the extras. I had a duck that sat 14 eggs (12 hatched) and some of the little farm hens had big broods of at least 12. Go for it!
Not keeping any RIR girls? Have heard very good things about them. Should be able to sell extra chicks fairly easily, but it will be a few weeks before you can tell the sex. If they are good quality, you might be able to sell in trios too.
Go chickies!!
PS. You don't want an incubator. . .
YET! Just wait until you experience the fleeting joy of those tiny little fluffy darlings. Enough to melt your heart! Then we'll see how you feel about it. Very addictive, chickens.