Many brides have dreamed of coming down the aisle to "Here Comes the Bride". It's almost impossible to be too dramatic. However, there are a couple of points to be aware of with this piece.
Most brides tend to scoot down the aisle faster than they're supposed to, so the A part (ending at measure 20) is likely all the harpist needs. If this is a little too short, consider repeating the last phrase of the A part, indicated by the Optional Repeat.
Only if the wedding party is proceeding quite slowly should you launch into the B part, as it changes key and must be resolved by the A-2 section at measure 29.