The time required between the block-in layer and the oil detail layers to complete a painting depends on the medium used for the block-in. If acrylics are used, then a few minutes only. If alkyd fast drying oils are used, perhaps hours or the next day depending on the colours used. If regular oils are used, then a lot depends on the mediums used. i.e. Liquin and white spirit aid the painting to dry quicker; linseed oil can take many days to a week depending on many factors. The painting should be very dry to the touch before the detailed oil layer is started.