、、。
Yukiko, starting tomorrow, it's fine if you just come in on Tuesday, Thursday, and Friday shifts.
Literal
Yukiko-chan [topic-は], tomorrow-onward, Tue-Thu-Fri [genitive-の] shift [in-で] come-to-work [do for me-くれれば] good [because-から].
A workplace instruction delivered affectionately, thanks to the ちゃん diminutive. 明日以降 ('from tomorrow onward') is a temporal frame — 以降 ('from X onward, and after') marks a time or date as the starting point. The frame ~てくれればいい ('if you do X for me, it will be fine,' 'it'll be enough if you X') combines ~てくれる (favor from someone) + ~ば (conditional) + いい (good). It's the standard way to say 'all you need to do is X.' The final から is explanatory/reason — 'because [that's how it is].' The abbreviated day notation 火木金 ('Tue Thu Fri') drops 曜日 ('day of the week') for brevity.