Clock time, days and the question of when に is required and when it is not — the rule turns on whether the time word is an absolute point or a relative one.
Also known astelling time japanese時間when in japanesetime particle ni
Hours use 〜時, minutes use 〜分. 今 何時ですか = “What time is it now?”
いま くじじゅっぷんです。
It's 9:10 now.
Counters 時 (o'clock) and 分 (minute) attach to numbers. Several readings are irregular: 4時 = よじ, 9時 = くじ, and 分 becomes ぷん/ふん depending on the number.
In the textbooksMinna I, lesson 4Genki I, lesson 1
もう + past (〜ました) = “already done”. “Not yet” is まだ + 〜て いません — NOT the plain past negative.
I have already done the homework.
No, I haven't done the homework yet.
〜ました covers both “did (yesterday)” and “have already done”. With もう (already) it means the action is complete.
For “not yet”, don't use ませんでした (that is a finished past, “didn't”). Use まだ … て いません — the action still hasn't happened.
In the textbooksGenki I, lesson 9