The owner likes the shop and then remembers the five hundred products. They are in a notebook, or in a spreadsheet named FINAL-final, or inside a till program whose vendor wants a renewal before they will export anything. Moving feels like a month. It is an afternoon if the list is already a list.
What has to come across
A product needs a name and a price. A stock count if you trust it. A size or a colour if the thing is not one thing. A photograph can wait a week; a wrong price cannot. History of every sale since 2075 does not need to come across on day one. You need to sell tomorrow. The old books stay in the cupboard for the argument about last year.
If twenty seconds is enough to type one row, five hundred products are 10,000 seconds, which is 167 minutes, under three hours. That assumes the sheet is already tidy. If each product instead costs two minutes of hunting through a notebook, the same five hundred are 1,000 minutes, which is a full day and then some. The second number is the assumption. The first is arithmetic. Do the tidy sheet first, even if the tidy sheet is a fresh Excel with two columns.
From paper
Read the shelf, not the memory. The notebook and the shelf disagree, and the shelf is what you can sell. Type the name as the customer should see it. Put the selling price, not the cost, in the price. Cost can live in the cost field if you know it. If you do not, leave it empty rather than guessing, because a guessed cost becomes a lying profit.
From Excel
One row per thing you sell. A red kurta in M and a red kurta in L are either one product with sizes, or two products. Sizes are the better shop if the photo and the description are the same. Do not make a product per colour if colour is an option. There is no magic importer that guesses this. Someone who knows the shelf has to decide it, which is why the afternoon is a person and not a file upload.
From the old POS
Ask for a product export before you pay the last renewal. Names, prices, barcodes, stock. If they will not give it to you, photograph the product list off their screen and type. Do not wait for a perfect migration and keep selling on a system you have already decided to leave. Run the new counter beside the old one for a week. The 7 free days of Pro are enough to ring real sales and see what you forgot.
Sales you make after the move export as a spreadsheet for the accountant. The old year's sales stay where they were. Closing the day is the habit that replaces the notebook, once the products exist.