Read A Date Rather Than A Line VBA Macro

I have the following code which reads line 54 (row 54) in a spreadsheet and calculates the following using data in subsequent columns. Sometimes the data I need isn't always in row 54, I would rather have the macro read the data in Column A[AB] that is on line 54...sometimes on 53.

The date is Sep-09. How can I make it read this rather than AB54. I think I just need changes @ the top (ie Dim rng as Range, Set rng = [AB54]).

Sub Profile_info2()
Dim rng As Range
Set rng = [AB54]
rng.FormulaR1C1 = "=RC[-12]+R[-1]C[-12]+R[-2]C[-12]"
With rng.Offset(0, 2)
.FormulaR1C1 = "=((RC[-28]+R[-1]C[-28]+R[-2]C[-28])*4)/((RC[-25]+R[-1]C[-25]+R[-2]C[-25])/3)"
.NumberFormat = "0.0"
End With
With rng.Offset(0, 3)
.FormulaR1C1 = _
"=((RC[-15]-RC[-29])+(R[-1]C[-15]-R[-1]C[-29])+(R[-2]C[-15]-R[-2]C[-29]))/(RC[-15]+R[-1]C[-15]+R[-2]C[-15])"
.Style = "Percent"
.NumberFormat = "0.0%"
End With
rng.Offset(0, 4).FormulaR1C1 = "=RC[-8]"
With rng.Offset(0, 5)
.FormulaR1C1 = "=(((RC[-17]-RC[-31])+(R[-1]C[-17]-R[-1]C[-31])+(R[-2]C[-17]-R[-2]C[-31]))*4)/((RC[-28]+R[-1]C[-28]+R[-2]C[-28])/3)"
.Style = "Percent"
End With
End Sub