You get the HBD in advance, so there is no risk from HBD dropping. Do the conversion if HBD>1.05 and sell the HBD you get immediately, locking in the profit above 1.05. The risk of the 3.5 days comes in from HIVE possibly dropping and losing more of your collateral), but that mostly hasn't happened (other than off the brief spike up to $1+ and back down).