From a reader:
Someone asked me today.. "what if after consecrating the bread the priest put it in a monstrance and had 30minutes of adoration before continuing with the mass?"
Every part of me wants to say this shouldn’t be done but I can;t really think of any reasons why… it would seem legitimate because the priest plans to continue with Mass after.. but I don’t know I haven’t really looked into it very far.
First, you create a serious problem about the two-fold consecration, which is essential for Mass to be Mass.
Mass is Mass and Exposition is Expostion. We need both (pace McBrien),but they should not be confused.
On the other hand there was something called Mass coram Sanctissimo, Mass in the presence of the Blessed Sacrament Exposed. This was usually done in the context of Forty Hours Devotion. If the older rites of Forty Hours are to be used, it seems that a Mass coram Sanctissimo could be celebrated. Authors are divided, but it seems to be so, for Forty Hours was the only time this form of Mass could be used.
But this would be a Mass which begins with the Host already exposed in the monstrance before Mass would begin.