"Am faint o'r gloch dych chi'n codi?"
Translation:What time do you get up?
"At what time?" and "What time?" both sound fine to me. Regional differences in usage, perhaps.
Would "Am faint o'r gloch dych chi'n wedi codi heddiw?" be "What time did you get up today"?
present perfect: Am faint o'r gloch dych chi wedi codi heddiw? = "What time have you got up?" (sounds a bit odd)
simple past: Am faint o'r golch codoch chi heddiw? = "What time did you get up?"
It's literally: "At how many of the bell...". I guess it may come from hearing the church bell.