You will only be classed as trading at the date of your first invoice. I would forget about an accountant at this stage. Do a simple spreadsheet, months along the top sales and costs down side and enter the amounts for each month. This is adequate at the early stages. You then deduct your expenses from your sales to give you your gross profit. With these figures and your tax return form, go to your local tax office and they will help you, they are very helpfull.