Only quotes with a status set to ‘Won’ will appear in the forecasts. ‘Won’ quotes appear in the forecast when the payment is theoretically expected. This date is set according to the ‘Expiration Date’ (date on which the customer accepted the quote and that you have set the status to ‘Won’) and the ‘Payment Terms’ of the quote.
For example, if the expiration date of a quote is June 1 and payment is due 30 days, it will appear in the forecast for the first week of July.
Please note, if you frequently use quotes, be sure to convert your quotes into invoices rather than creating invoices manually. Otherwise, you could end up with duplicate forecasts.