What's the best way to import data into StockTrim when I've recently started with a new inventory management system?

If you've just started using a new inventory management system, and most of your sales history is not in here, but in a different source, you can still import this into StockTrim easily. 

Firstly, you'll sync StockTrim with your new inventory management system. This will import your products catalog and your most recent sales (since your implementation). 

Then, import your older sales history via CSV (the template is on the load data screen in StockTrim). Just make sure that the ProductId in the sales orders file matches the product code in your IMS, and then the sales history will be imported. This will only need to be done once, since your new sales will be recorded in your new IMS and automatically load into StockTrim from then on.