Yes, the usual order is to install the 4.5 mm spacer, the cassette and then the lockring. The only problem can be if the cassette had long bolts or rivets that protrude past the largest cog and keep the cassette from sitting flush on the spacer and prevent the lockring from threading on. So, you can remove the rivets/bolts first and install the spacer behind it or install the spacer after the cassette and then add the lockring outside of it. Any small cog 12T or larger will clear the spacer.