A word of warning regarding Cockroach bombs....
There has been many a Restaurant blown up by the owner trying to save money using aerosol cockroach bombs.
The type that you set off and leave the premises are extremely dangerous if used around any naked flame. Eg, a pilot light in a gas heater etc or even a fault in an electrical appliance that may cause a spark.
Off on a bit of a tangent....I am amazed that the OP on this very forum bangs on and on about electrical work only being done by LICENCED operators then comes on here wanting advice about pest management procedures which again, is a field whereby a LICENCE is required to carry out such work.
You want the job done properly and safely then HIRE a LICENCED PROFESSIONAL.