As the first activated ability resolves, it counts the number of times that same ability from that same Bronze Cudgels has resolved that turn, including that activation. For example, the first time the ability resolves in a turn, it will grant +1/+0 until end of turn, the second time +2/+0 until end of turn, and so on.
A resolution of the ability counts even if Bronze Cudgels was attached to a different creature or no creature at the time. A copy of the ability (created by Lithoform Engine, for example) will also count toward the total. An ability from another Equipment with the same name doesn't count towards the total, nor does an ability that's been countered.