Create new database with large initial size
Unless you're using Instant File Initialization, SQL Server must zero out all sectors for the files.  This is a very time consuming process, especially for 250 GB (data+log).  In order to speed things up, enable this feature and then SQL Server will not zero out the space for the data files.

Please note, SQL Server will always zero out the log file, so you will still be limited by that. Another reference for log file initialization