You do of course realize that we can work those in later? All the sheets that have been mentioned so far have been ones for Servants, who shouldn't be overly affected by the original plot details for this until they're summoned. Granted, you've mentioned the thing about catalysts and people do seem to be rushing them out, but it's general practice in this kind of RP to have Servants ready to go and again, people do tend to get worried when you say reserving a Class position only counts for so much. 

Just sayin'.