Yes, in most (I think) contexts - yes. Unless something in the sentence makes it clear that it's not the situation:
"Lubię czasem zjeść coś słodkiego" (I like to eat something sweet sometimes)
"Muszę przeczytać jedną książkę w każdym tygodniu tego roku" (I have to read one book every week of this year)
I'm not sure if it's grammatically like that, but you can at least treat 'wieczorem' here as an adverb. Russian definitely does so with words for "in the morning/day/evening/night". Polish mixes it up, but you will have rano/rankiem, przed południem, po południu, wieczorem, nocą/w nocy. So some of them have prepositions, and some of them behave adverbially.
I know this is late to answer but it's wrong because of the preposition. English time prepositions are weird. In English you say:
IN THE morning
but AT noon
IN THE afternoon
but AT night
IN THE evening
but AT midnight and AT dawn
There are some exceptions but they are outside the context of the example sentence so they don't matter here.
Well, 'night' can be sometimes used in a bit surprising way to non-natives, especially considering the word 'tonight' which for sure can refer to the evening. But here, you are right - it's definitely too much to accept. I'll delete that option.
And "at evening", as I was told, is not correct as well.