If you are talking about sending it outside of the actual invoicing system, the only way I can think of you being able to do that is to send an invoice to yourself, then go back in the invoicing system, locate the invoice, click more, and then click share. You can then copy and paste the URL into an email to your customer.
With that said, I'm not sure why you would want to go outside of the invoicing system unless you are being charged less for your processing elsewhere. They don't charge for invoices that are paid with cash or check.
Now, if you are talking about sending an invoice right away from the invoicing system, make sure you choose "Send Immediately" next to "Send" and under "Frequency" on your invoice. There's no need to schedule it. It will send immediately. Scheduling is for when you want to send an invoice at a future date. Hope this helps!
