They assume that children should not start gaming, reading comics or doing other non-productive things like ゴロゴロする
from the morning, noon or any time in the daytime.
[Edit]
After thinking for hours, I realized it's not right to translate から
into 'from' here. The feeling or sense of から
seems different than 'from'. It's interesting to know that "from the daytime" doesn't sound right in English.
から
comes with anything like morning, noon, daytime, night, today, yesterday and so on. The thing is, you can say Xから
even if it is time of X. So something like "from the daytime = in the daytime" happens in Japanese.
In your sentence, the kid started ゴロゴロする
in the daytime AND the speaker is also saying that in the daytime. Also, yes, から
can make connotations like "from such a time".
Other examples:
[朝から]{あさから}[勉強]{べんきょう}するの?
- [said in the morning] Are you going to study (start studying) now?
- Do you study (start studying) in the morning?
- Will you study (start studying) in the morning?
[朝]{あさ}に[勉強]{べんきょう}するの?
- Do you study in the morning?
- Will you study in the morning?