One of my starting seven once had a female cave crocodile as a pet. Goddamn, for once it wasn't a grackle or some shit.
As a proud Cave Croc Rancher and owner of a few hundred beasts, I can testify that the eggs, fertilized or not, stop dropping until you butcher a few of 'em. Build a few nest boxes, designate a pen and chuck a few females in, lock the doors, and forget'em. Open doors every few years to cage the hatchlings (mass cage and deploy them during the first year unless your dorfs all have over 9000 strength) It's quite impossible to thin 'em out save for pitting them into lava, with three butchers and kitchens, five craftsdwarves workshops. I have to dump all non-masterwork bolts.
If there is a formula to allow you to buy a breeding pair at embark without adding 999999 points (damn embark screen teasing me with tame great eagles as buyable pets and the the civ only offers great eagle MEAT afterwards), use it.
Otherwise, breach the cavern ASAP, cuz there's gonna be some waiting. Cave creatures "cycle" pretty fast once you have an efficient (read : killing everything that isn't a cave croc) military. I'd pass Rutherers - their reproduction rate is not worth it. I had like ten of them, penned them at the bottom of a dry moat situated under a retractable bridge, they all died to four goblins who'd withstood five Z-levels' worth of broken legs. Arena purposes maybe, against naked enemies... With fifty crocs and so many to spare inside the "no-lag quantum shared cage", you don't think about equipment anymore. I certainly wouldn't even think about sending less than thirty crocs against even one goblin, haven't tried one-on-ones to be honest, but opening a crocsplosion cage from a lever in your dining room is the dorfiest thing in the world.
Final argument : ☼cave crocodile egg roast [169]☼ = 50-60k☼ a pop.