overstayed 1 day or not?

I have one year business M, 90 days multiple entry. I arrived China 28 March, and will leave 26 June. the policy is the 90 days starts from next day after entering China which is 29 March, and will leave China 27 June via Guangzhou and return same day. The latest policy was posted on wechat by visa agent. eg given 30 day visa, arrive 1st July, first day starts from 2 July and must leave by 31 July 2400. I counted 29 days.....
Either I am perfect 90 days, or overstay one day. So I will go HK but will they let me back in?