USA - confidential informant question

[teddybearpicnics]

if someone is a confidential informant and they buy from a house...does the person get busted by a search warrant for the house within 10 days. or do they wait for a few months and then put a warrant out like they would if the arresting officer actually saw the deal go down. because under my knowledge the officer doesn't know that the informant actually got the substances from the person that the c.i. said because the officer couldn't see the actual deal go down..and there could have been a number of people in the house..so that makes me think they they would only be able to have a case from what illegal substances/stuff they found with the warrant. unlike when the officer is parked a few yards away and actually saw that person get in the c.i's car? i am asking this because my roommate thinks that someone narced him out, and if they need to do it by way of a house warrant then it's impossible because it's been over 10 days...but if they just wait like they do for an open air bust i am going to be sketched out about keeping anyhing in the house.

[old hippie 56]

Either that, or he goes before a grand jury to get a indictment for the accused which could takes days or weeks.