I've been trying to make proper sentences using the word きょう when I realized that I'm not really actually sure when I'm suppose to mark it with は. I know relative time expressions tend to stand alone meaning it's not followed by に and because of this its not uncommon for it to be followed directly by another word with no particle in between. This is where I start to get confused however when I see a sentence like this one
明日{あした}きます
and then a sentence like this
今日{きょう}は 京都{きょうと}に いきます
I'm pretty sure the reason I'm having a hard time understanding this is due to my terrible understanding of は, regardless any help on when I should mark a time like this with は and when it would be better left unmarked would be appreciated.