There is no standard time since the time to complete a Sudoku is dependent on how hard it is. It can take from minutes to days ... many days. There are several sites where you can see times posted from other people (such as
http://www.sudoku.com.au/ ) or an average solution time (
http://www.sudoku.org.uk/competitions.htm ). Another good site where you can also discuss solutions is
http://www.sudoku.org.uk/competitions.htm . Good luck and if you need help there are many here who will help out.