When should pilot join holding pattern?

[jungping]

Suppose you are being radar vectored to ILS final approach course, runway 09.
The initial approach fix(IAF) of the ILS approach is at 14 nm west of airport, and there is a holding pattern depicted at IAF(west direction). And you are at 40 nm southeast of airport(e.g. 140 radial 40 nm from the airport).
Now you are cleared to direct to IAF, and also cleared for ILS approach runway 09.
My question is what you will do when you reach IAF? You will proceed ILS approach or you will join holding pattern then when you pass the IAF the 2nd time you proceed ILS approach?
Under what circumstances should pilot join holding pattern and then proceed ILS approach?(exclude altitude too high)