i'm new to Billings and would like to set the invoice number of the first billings invoice so it is in keeping with my current invoice records. does anyone know how this is achieved?

Information about invoice numbering is available in Billings Help (choose Help > Billings Help and search for invoice number). It's also mentioned in the Quick Start Guide which came with Billings: http://www.billingsapp.com/support/Billings2QuickStartGuide.pdf.

Invoice numbering can be customized in Billings Preferences. Choose Billings > Preferences, and be sure that you are on the General pane.

Billings does increase the number with each invoice. You can use special characters to represent day, month, and year, if you want your invoice number to reflect the current date. These characters are documented in the aforementioned Quick Start Guide.

HTH,