Date calculation based on several dates

I would greatly appreciate any help with this calculation. In column e I have a program start date. In column f is a graduation date, in column g is the date for leaving program and in column h is a termination date. In column i is the formula dateif for months and column j is the formula dateif for the days formula. These caluculate for the program start date and the graduation date. But I would like them (i and j)to calculate from the program start date and then whatever column has the next date, whether it be f, g or h.
Thanks
Michelle

perhaps, for I2

=DATEDIF(E2,IF(ISNUMBER(F2),F2,IF(ISNUMBER(G2),G2,H2)),"m")

and similar in I2 for days

Perfect - Thank you so much.
Michelle