I've installed steam app and apply it as steam guard shield. Now I cant trade anything, cause I have mail confirm for trades. But now all confirms come to phone and as it has 7 days restriction (as new device) I cant verify anything.

Ok, I thought I just need to relax and wait for 7 days. But... 7 days restriction shows me as error only for manual verify trades. And if I use "Confirm" (or something like that, cause of my translate) bookmark at my phone, which contains my orders waiting for verify - then steam app shows me "Confirmation error. You device has wrong date and time setting. Its unable to proceed untill issue wil be solved". Btw I haven't any problems with date or time at my phone

Now I wonder if it just error decription bug mean I still should wait 7 days pass or steam app realy decided to get fun with my suffer? Do anyone faced the same problem?

I have never seen that myself but this probably is just an error because you have not waited 7 days yet. Steam's error message has not always been helpful. You should ask Steam support too but you are not likely to get an answer in 7 days.