Custom Sorting a column by Date....and Text

I need to custom sort a column. I have 3 different types of data in the column.
First - multiple dates, Second - "TBA", and Third - "ASAP". What I need is when the column is sorted the "ASAP" rows will be first, the dates (sorted) will be next and finally the "TBA"s. I have been trying to use a custom list.....? Does anyone have any ideas? Thank You