Standard SHM time intervals to memorize:
• Mean position (\(0\)) to half amplitude (\(A/2\)): \(t = T/12\)
• Half amplitude (\(A/2\)) to extreme (\(A\)): \(t = T/6\)
• Extreme (\(A\)) to half amplitude (\(A/2\)): \(t = T/6\)
Here, the particle moves from \(A\) to \(A/2\), so \(t = T/6 = 4/6 = 2/3\text{ s}\).