My DH does this too! Must be a man thing! Basically, they just LOVE to tell women what to do, and they think they know best!
I say 'just gonna wash up.' He says 'nah leave it til the morning.'
I say 'I'm gonna have a shower.' He says 'don't bother now, have one in the morning.'
I say 'I'm going to weed the flower bed at the front.' He says 'nah, just leave it, and sit and watch TV.'
I say 'I'm going to lighten my hair.' He says 'nah, don't bother, do it another day.'
I say 'I'm going to wash the car it's grubby.' He says 'just leave it, we'll take it to the car wash soon.'
It gives me the rage.
I think 'I am informing you that I'm doing it, not asking for your fucking OPINION or PERMISSION.' 
I just don't tell him ANYthing now (when I am about to do something,) I just do it. Coz I get SO fucked off with hearing 'nah, don't do it, just sit down... do it later/tomorrow/next week!!!'
Like some other posters husbands, he also has to be contrary with things I do and say in other ways, like I say 'I will put the new little seedlings in the kitchen window,' and he says 'why not put them in the dining room window?' And then I say 'I will just put my red cardigan on' and he says 'why not put the blue one on?' I get the cat some sheba food to eat, and he says 'why didn't you give her the Felix? She likes that.' (SHE LIKES THE SHEBA TOO!) When I put a shoe rack I built in the hall cupboard on the left hand side, he said 'why didn't you put it on the right?' 
LOADS of things like this. For 30+ years. I don't know how I haven't murdered him.
It's SUCH a relief to see that many women have men the same and it's clearly just a 'man thing.' Ergo, HE knows best, and HE is the boss man. And no WOMAN can possibly know better than him about ANYTHING. (In his head!!!)
Seriously, why? WHY do men do this? Seems like a lot of men do! WHY?
Do they really think we need - or want to be told 'NO don't do that,' when we have decided to do something? 
Like other women on here, I have always ignored him, and done what I want, but it's still very annoying!