Since 3rd grade math relies on the concepts that were learned during kindergarten, first and second grades, don't be afraid to start your child at a lower level.
Do choose worksheets that are appropriate for the child's level, since children can get discouraged easily, if they are unable to perform the activity. Well illustrated worksheets with cartoons are also more likely to appeal to children. Worksheets that use common situations children come across at home, school, in the market place etc and that use common objects known to children would be more relevant.
A homeschooled student will receive the absolute best education possible without the expense and overhead of ordering multiple copies of hardcopy texts. Textbooks will not need to be discarded at the end each school year.
The homeschooling education should include a strong textbook foundation as well as a thorough instructor and lesson plan. The home school education should not be exclusively based on education of the instructor or limited to a curriculum purchased.