daddylonglegs wrote...
This formula will give next first Tuesday at noon, based on a cutoff
of noon on the 1st Tuesday

=FLOOR(EOMONTH(FLOOR(A1+3.5,7)-4,0)+4,7)+3.5

similarly this will give last Thursday at noon also based on a
cutoff at noon on last Thursday

=FLOOR(EOMONTH(FLOOR(A1+1.5,7)+5,0)+2,7)-1.5

Note: only works correctly with 1900 date system
....

Note also that in Excel 2003 and prior it requires loading the
Analysis ToolPak add-in, since EOMONTH isn't a built-in function in
those older versions.