The Touchstone feat (from Sandstorm, p.53) lists the following as Prerequisites:
Knowledge (local) 8 ranks for the area in which the touchstone lies, OR possession of a touchstone key (a portable object native to the touchstone’s area and worth at least 250 gp). To forge a link between yourself and the touchstone, you must spend a day in meditation, spending 10 XP and 250 gp in material components. Alternatively, the key object for the touchstone can be destroyed as part of the ritual, in place of the material components. (Emphasis added)
It is noted that this feat could possibly have been intended to be an update from the previous Planar Touchstone feat (Planar Handbook, p.41) which is almost exactly the same, however the text grammatically indicates that both the skill ranks and the object are required. However, since the feat name is slightly different, it could be argued that they are technically different feats.
A prerequisite of 8 ranks of a skill would normally place the earliest opportunity to take the Touchstone feat at level 6 (unless a given character build happened to have a bonus feat available right at 5th level).
Given the “OR” in the quoted text, what character level then is the earliest that the Touchstone feat can be taken, assuming at a minimum that the required object is in hand?