When making plans, which word indicates a preference for timing?

The word "preferably" is the most appropriate choice for indicating a preference for timing when making plans. It suggests a desire for something to happen in a particular way or at a specific time that is more suitable or appropriate than other options. For example, if someone says, "We should meet preferably in the afternoon," they are expressing a clear preference for that time over others.

The other words, while related to positive qualities, do not specifically convey a preference for timing. "Ideally" suggests a perfect or optimal scenario, but does not emphasize a specific preference. "Favorably" implies a positive view but is more about general approval rather than timing. "Desirably" points to something being wanted or wished for, lacking the direct indication of preference as seen in "preferably."