A flow conduit may have at least one orifice, which conduit is in the vicinity of a flow source. The source is at least partially covered (and flow blocked by) an optional temporary coating or barrier (e.g. filter cake). The flow pathway between the orifice and the source is temporarily blocked with a degradable material. A delayed degradation material layer is present over or covering the degradable material. The delayed degradation material layer degrades at a rate slower than the degradable barrier. The degradable material and delayed degradation material layer disintegrate (e.g. via time, temperature, a solvent). The degradable material optionally produces a product that removes the temporary coating. The method is useful in one context of recovering hydrocarbons where the flow conduit is the casing or liner of the well and the flow source is a subterranean reservoir where the coating is filter cake.