There is no definitive answer to your question, but some of Craig Urbine's (II's former rep to TUG) posts on the old BBS give a pretty good indication.
How early you deposit your week is just one of the factors that affect how strong a trader your week is. For many resorts, depositing a week 9 months in advance will not be noticeably different for trading power than depositing it a full year in advance.
On the other hand, the difference in trading power between an early May beach week in Hilton Head and a July beach week in Hilton Head is huge.
Thus, other things being equal, a July Grande Ocean week deposited 9 months ahead should trump a May Grande Ocean week every time, no matter how early that May week was deposited.
The other factors, besides date of deposit, that affect trading power are: (1) the supply and demand of the week being deposited or offered through Request First, (2) the supply and demand of the week being requested, (3) the quality, facilities and overall experience offered by that week, (4) the date the exchange request is submitted to II (The earlier of two identical requests will be the winner) and (5) a comparison between the week relinquished and the week requested (sleeping capacity and unit type).
Note that the week being requested enters into trading power because the exchange must be a "comparable exchange under II's unpublished guidelines.