Most likely you need to wait longer. It takes a while to load in 330 million sequences, and then it also takes time to search against that database and to create all the alignments.

To speed things up: 1) specify a meaningful E-value as calculating all alignments for E=10 takes time (say, -evalue 0.01); 2) if you don't need all alignments, specify a number that you need (say, -num_alignments 500); 3) if you need to know only in general what matches your protein but don't need absolutely all protein hits, use a database that is trimmed at 90% identity (for example, UniRef90 at ftp://ftp.uniprot.org/pub/databases/uniprot/uniref/uniref90/ ). This will speed up the search at least twice, possibly more.

PS I suggest you specify an output file (-out blastx_output.txt), as searches against the nr database tend to produce voluminous outputs.

PPs It is almost certain that you don't need to run this command as sudo.