M.M.
At 8 weeks I started letting my son fuss a bit to get himself to sleep. I didn't let any long crying jags happen. But I'd feed him, swaddle him and then put him down. I'd let him fuss for about 10 minutes before I went in to him. If he was really crying, I'd go comfort him. But he's at the age where you can set the framework for sleep training. Start the associations of the routine you'll use for bedtime, associate the crib with sleep, etc...
CIO generally starts around 4-5mos. 8 wees is waaaay too early for that. But again, you can begin the pattern. With any luck, starting now, you won't have to sleep train at all.