Коли повезет, так и бык теленка принесет

When circum stances are favo(u)rable, you can be successful See Где счастье поведется, там и петух несется (Г), Одна удача идет, другую ведет (O)

Cf: If luck is with you, even your ox will give birth to a calf (Am.). If you are lucky, even your rooster will lay eggs (Am.). When man has luck, even his ox calves (Br.). Whom God loves, his bitch brings forth pigs (Br.)