I just applied level 2 verification and i have also uploaded photo ID and picture of myself holding ID, but my status is still incomplete.
Is this a natural occurrence or I should wait for manual approval by poloniex?
Well, it used be all super fast but now poloniex is definitely really, really incompetent in terms of its ability to process customer requests.
Ify ou look on discussion boards on reddit or scam accusations here you'll see a ton of posts about poloniex either delaying withdrawals, deposits, not approving level 2 verification, or all of the above for some people.
You shouldn't wait for higher limits, start withdrawing as quickly as you can. I actually haven't seen anyone being approved by poloniex for lvl 2 since end of May, and it's probably not going to happen for you any time soon either. The fact that their trollbox is removed as well just further shows that they want to cover up the whole thing. Late stage craptsy scam was somewhat the same situation as polo is right now, scamming user deposits, selectively as it seems.