Which step should occur first when laying block to the line?

When laying block to the line, the first step involves preparing the surface for the blocks by spreading the mortar bed joints. This is crucial because a proper mortar bed ensures a strong and level foundation for the first course of blocks. If the mortar is not spread adequately at the outset, it can lead to uneven courses and structural issues later on.

Prioritizing the spreading of mortar helps in achieving correct height and alignment while laying the blocks. It creates a consistent bond between the blocks and the base, which is essential for the integrity of the wall being constructed. After the mortar is properly set, the subsequent steps, such as setting the first course of blocks and aligning them, can be executed more effectively.