There is quite a bit of flexibility built into land management plans for fell years. There is no sure fire way to know when felling is planned unless you seek permission. Coupes that are up for harvesting can be pulled/substituted at the last moment.
Your best bet is the LMPs, observing the maturity of timber, observing the increase in blown timber as terminal height is reached, or engaging a local forester in casual chat in the area. Paint marks on trees appear at mensuration, but that happens several times a rotation, so isn’t a good guide for felling. Coupes going to market and therefore very likely to soon be felled have their boundaries marked in white tape with long tails.
Remember there are multiple activities in a productive coupe – planting, beat up, thinning, harvesting, roadbuilding, deer control – all of which shall ignore cheeky trails.