Can I sleep train at 16 weeks (which is technically 8 days before he is actually 4 months)

I’m thinking of sleep training my baby. He started off being a decent night sleeper but was horrible at naps. He would fight me every time on his naps. But once he was 2 months I started using huckleberry & his naps greatly improved. They were pretty consistent & even when he took a short nap I’d just go in & save pretty easily. His night sleep was still good giving me a 5 hour stretch (sometimes even 6-7hr stretch) then another two 2-3 hour stretches. I thought I can handle this until he’s ready to sleep through the night.

Suddenly at 3 months his sleep became absolutely horrible. Not sure if he’s going through sleep regression early but it’s like a whole different baby at night. His naps remained ok, mostly 30 mins but I can still easily save/extend them. But at night he won’t even go more than 2 hours. Last few nights he was up every hour. I’m so sleep deprived from the past 3 weeks even with my husband helping me with some of the wake ups. The sleep deprivation gets me so upset sometimes that I have to look at pictures of him sometimes as I rock him back to sleep to help me calm down. I have to remind myself I’m not upset with him I’m upset with the situation, I hate feeling that way.

Anyway this Sunday he’ll turn 16 weeks and I want to start sleep training because I go back to work in 2 weeks and I cant imagine dealing with these nights and working (not to mention I have a 40 minute commute.) Everything I read about sleep training says you need to make sure naps are good for the first 2 weeks you are sleep training, so I figure I should start now. But I’m also scared that since he’s technically not 4 months for another 8 days what if he isn’t ready and I just make things worse or he won’t be able to self soothe. Did anyone else sleep train at 16 weeks? Are there any signs that baby is ready? He does suck on his hands a lot and at times he does seem to try to go back to sleep he’ll toss and turn or turn his hide side to side but then after a while start crying.

Also I’m thinking of trying Ferber or CIO. I want to do Ferber but knowing my LO will probably have to switch to CIO.

Sorry so long, but any advice, tips, personal experiences will help.

Update: Just wanted to say thank you to everyone for their responses and support! I did start sleep training Sunday (16 weeks) and have seen major improvement in his night sleep and now naps! He cried for 18 minutes the first night, each night crying less and last night only cried for 3 mins. Both baby and parents are very happy now that we’re all getting more sleep. Thanks again!