Bulk/Import invoices for multiple billable expenses

Bulk/Import invoices for multiple billable expenses

Hi,
I have recently started using Zoho books for accounting activities. i have some data backlog that i am trying to enter as soon as possible. I have been using excel and import to do bulk entries for recording payments received and billable expenses (different customers) but i am stuck in invoicing part. it seems there is no quick way to make invoices from billable expenses for different customers. I have to do it manually one by one which is very time consuming.
Currently I have about 500 billable expenses and each is for different customer.

I would highly appreciate if any user or support people have a solution to fasten the process.

Thanks.

Shaikh Abdullah