Contact shipper beforehand and ask their SG.
Setup my QT to same SG shipper stated and same temp as my DT
Float bag for 30 mins to equalize temp
Open bag and do a quick SG check to ensure shippers info was accurate.
If same, dump clown in (without the water).
If not same dump bag of water into a bucket, add 1/4 of that amount from QT. Continue adding quarter amounts every 10 mins until SG is on the mark or 30 mins since the time I opened the bag. Dump em in.
FWIW this is how I acclimate all my fish/inverts and never had an issue. Worth noting also I use a plastic colander to dump fish into then into tank.