It is important that you put date last so that it appears last in the sequential sum of squares in the ANOVA table. In the box for Save Model Object as enter Full.lm (ie this is the full model). Under the Results page/tab, check the box for ANOVA and save the fitted values in the dataframe. Click OK to run the regression. (verify that residuals are ok, then discard plots)
In the Report Window, you will have the ANOVA table for the Full Model. Verify that the df for date are 7 and not 1. Because we are treating it as a factor we should have 1 df for every dummy variable or 8 - 1. If it is treated as a continuous variable, the df would be 1 and something likely screwed up with the options() command earlier.
Save the Model Object as Reduced.lm. Under the Results menu, click the ANOVA box, but not the fitted values box. Click OK. The ANOVA table for the reduced model will be in the Report Window.
From the statistics menu, bring up the regression dialog. For the model formula enter:
Save the fitted values and rename then as fit3.