Setting up Kashflow online bookkeeping system for me with opening balances

I currently use www.xero.com for my own bookkeeping.

I would like to switch to www.kashflow.com or www.clearbooks.co.uk.

I need someone with experience of these systems to set up the opening balances up for me.

We are accountants ourselves but simply do not have the time.

I can provide a trial balance from Xero and a sales ledger report.

We have around 500 clients with around 200 of those with balances.

So it will be names, addresses and invoices that need entering.

As I use the accounting system all the time I need a clear cut off. So one evening would be good. To move from Xero to Kashflow.