Xinqiao Town is far from Jiangyin City but close to Zhangjiagang City, so you can take a long-distance bus from Shanghai Long-Distance Bus Station to Zhangjiagang (bus fare about CNY60) and then transfer another bus at Zhangjiagang New Long-Distance Bus Station to arrive at Xinqiao Town (bus fare about CNY6).

To go to Yiwu on the same day, the easiest way is to return to Shanghai from Xinqiao Town first since there is no direct bus from Xinqiao to Yiwu and only one bus from Zhangjiagang to Yiwu in the morning. There are many trains and long-distance buses between Shanghai and Yiwu.

Dear Mr.ABELLAOUI, Thank you very much for your reply. I have my itinerary worked out this way. Please let me know what you feel.
Shanghai to Wuxi by 6052am Train D182/D183 Then Bus to Xinqiao Town maybe about one hour. Please correct me if I'm wrong.
I will then return to Wuxi from Xinqiao Town about 2.00pm and take Wuxi to Shanghai train number D5509 at 15.01pm to get to shanghai at 16.10pm and then take The K537 Train from shanghai at 17.01pm to Yiwu to get there at 20.07pm.
This is what I have been able to find out on the internet but because I've never been there before I don't know if it will work, so please just tell me straight if it's not going to work. I will always prefer to take a Train than Bus unless it's not possible.
Thank you.