After green timber is sawn it needs to be handled correctly while it is drying or seasoning: otherwise it may crack, bend or twist. Timber is only seasoned when the last moisture in the centre of the piece of timber reaches equilibrium with the moisture in the air. It is better to keep the outside of the timber moist while the moisture moves slowly out of the core to maintain the capillary chain.
Keeping most of the timber moist also reduces rapid shinkrage and hence tensions in the wood which are the cause of cracking & warping. So the golden rule is: when drying timber keep it moist! This sounds contradictory but it is the reason steam is always pumped initially into a timber drying kiln.
So immediately after green timber is sawn seal it with a protective coat to slow the drying rate. You could wrap it in glad wrap or paint it - but the cheapest & easiest way is to coat it with liquid wax. This is what End Check is. Do this straight away. Next day is too late as the greatest drying takes place in the first few hours. Of course the most rapid drying is from the end grain and because of this the ends are most likely to split. Hence the name End Check.
But the rest of the board is drying too... so coat the whole board but pay particular attention to the ends. And another tip. Because you are trying to dry the centre of the piece and also the stresses are greater in thicker sections always cut the timber into boards as thin as you can utilise. This will reduce dramatically the seasoning time required and greatly reduce the chance of cracking and warping.