In July, President Buhari said he would wait until September to appoint cabinet ministers, so that new rules of conduct and good governance could be put into place.
Today is the last day of September, and Buhari submitted the names of his nominees today to the senate for approval.
From a quick Google search, I'm not sure what the new rules of conduct and good governance are, and whether they've been put into place, except for this: "a directive that all federal revenue-generating institutions, including the opaque state oil company, begin paying their revenues into a single Treasury account instead of a web of largely untracked private bank accounts." The oil industry is probably the main source of corruption in Nigeria, so his reforms in that sector are important. Buhari is also keeping the oil portfolio for himself rather than appoint an oil minister, which would ordinarily sound worrisome, but Buhari does have a "clean" reputation.