I really don't understand what this obsession with long championship reigns comes from. If you look back over the course of wrestling history during the 20th century, you'll find that most championships changed hands several times a year. In the various NWA territories, for instance, it's pretty rare to find a regional title that was carried for 6 months or longer. And, even if you did, it was usually by someone that was either the owner of a territory or something that had a LOT of clout within the territory.
Now for such titles as the NWA, WWF and AWA World Championships, reigns measured in years were pretty common up until the late 80s, as well as a few mid-card titles like the NWA U.S. and WWF IC titles. Those titles, however, seemed to be the exceptions rather than the rule. Lengthy title reigns don't work today because today's average wrestling fan doesn't have the attention span to even want to endure lengthy reigns.
Now, that being said, I think Rey should hold onto the title for a little bit longer, though let's not go crazy here. If Rey holds the strap for more than 3 months, half the people that frequent this forum will be screaming for his head. If a guy holds the title for a month or so, it's too short. If he's had it for 3 months or more, people are screaming he's had it too long. As far as length of reigns goes, there's really no pleasing anybody anymore. Vince McMahon will ultimately make the decision as to how long Rey keeps it by how much the crowd likes it, thereby how much money Rey as IC champ brings in.
And, quite frankly, that's exactly the right way a decision like this should be made. I hear people piss and moan sometimes about Cena's lengthy reigns as WWE Champion sometimes and it irks me. Cena made Vince a lot of money as WWE Champion, that's why he kept it for so long. If Rey can't bring in the bucks as IC champ, then he shouldn't be carrying the strap for long reigns.