Can I import invoices to bullet?

You can do a bank rec and import your bank data. If you’re moving from a product that’s the smartest way to do it. 
We generally give people converting over the following advice:
Run a Trial Balance on your existing accounting software.
1) Enter all your currently outstanding invoices and bills into bullet (only the ones with payment due – not the paid ones).
2) Take a look at the Trial Balance on Bullet.
3) Figure out the difference between the original trial balance you got from your old software and the trial balance in Bullet.
4) Enter these differences as a big manual journal entry.
After the above, your trial balance on Bullet should be the same as on your old software, and you’re all ready to go.
Hope that helps