Indonesia 30 visa-free access - Will I have trouble if I stay for exactly 30 days?

I'm planning to visit Indonesia, holding a passport that gives me visa-free access for 30 days (just like over 160 countries get).

From Wikitravel, there is a part that reads:

Also note that the days a visa holder is within Indonesia are counted with the day of entry being day 1, not day 0. This means that by 24:00 (twelve midnight) on the night of the day of arrival you have been in Indonesia for one day. If you enter at 23:59 (11:59pm) then 2 minutes later you have been in Indonesia for 2 days.

Immigration officials may claim that a 30-day visa-on-arrival means that you must leave before 30-days (ie on the 29th day or before). Be careful about this.

My travel dates are as follows:

Arrival: May 9 (around 10AM). Departure: June 7 (around 2PM) at a different airport.

Including May 9 and June 7, I would have stayed in Indonesia for exactly 30 days.

In my last visit, I have a visa-exception stamp that reads:

Permitted to enter and stay for 30 days from date shown above

I have doubts about the above Wikitravel quoted paragraph, about the part that says I must exist the country on the 29th day.

I would appreciate if any of you have experience with this. I'm not going to risk an over stay or an entry-refusal, and I have the option to arrive on May 10 or later. From my experience, a 30 days visa means I can stay 30 days, so I shouldn't probably spend a considerable amount money to purchase a new ticket (they are separate tickets, and cost works out cheaper to buy a new one).

Is there any chance that I will be denied entry or marked an overstay with this, specially considering how the immigration process in Indonesia? I have asked a similar question about a Schengen visa in the past. I was given a 20 day visa, and I exited on the 20th day, with no issues at all.

Thanks everyone in advance.