In short
On Slaby, add items at the counter and save them as an estimate instead of billing. The estimate gets its own EST number and a valid-till date, prints on a roll or A4, and goes to the customer as a WhatsApp link. When they are ready, open it and bill it; if prices changed meanwhile, you see the difference first.
How do I make an estimate at the counter?
Build the bill as usual: scan or search items, set quantities and add the customer. Instead of Pay, choose Save as estimate. It is also in the Ctrl+K menu.
Estimates have their own number series, starting EST-, so they never use up your bill numbers. A B2B estimate can carry the buyer's GSTIN and place of supply.
How do I send a quotation on WhatsApp?
Open the estimate and press Send on WhatsApp. The message carries the estimate number, the total, the valid-till date and a link the customer can open. You can also copy the link, or print the estimate on a roll or on A4.
How do I turn an estimate into a bill?
Open the estimate and bill it. Slaby checks today's prices: if anything changed since the estimate, it shows the old and new prices and you accept them before the bill is made.