I do not understand your question fully. But following the csvWrite documentation and the date documentation. You could do someting like this
filename_with_date_string = date() + ".csv";
directory_path = TMPDIR;
// Some matrix you want to save
M = [1:10] * 0.1;
// Create the file
file = fullfile(directory_path, filename_with_date_string);
// Fill it with your matrix
csvWrite(M, file);