Accent on Imperative forms

I had as a rule that imperative forms were stressed as the 2nd. person singular is, sometimes I see that like the 3rd. person plural. No difference. But I find that sometimes this rule is not so regular. Finally I have found that are exceptions to this rule that must be kept in mind. I ask: There is some, though not very strict rule for this matter, Accent of Imperative?
Thanks

EDIT: Oops I misread that post.

The imperative stress falls on the same syllable as it does in the first person singular.

shifting in pres. tens:
ношу́, но́сишь носи́

fixed on stem in pres.:
чита́ю, чита́ешь, чита́й
изба́влю, изба́вь
откро́ю, откро́й

always on ending in pres.:
веду́, ведёшь, веди́
говорю́, говори́

I can't think of any exceptions. Look at
е́ду е́дь е́дьте
even! (it's not grammatical, but people say it.)

Пионер, бу́дь готов!

Thanks for your help