Questions for applying to full time jobs for the first time

I am going to be graduating in May and so I have started the job hunt. How long does it usually take for companies to respond to an application? I applied to some a week ago and I haven't heard anything back yet. Do companies usually respond slower around the holidays? I am a worrier and so when I haven't heard anything back I start to fear that I won't hear back from these companies. How many jobs do you usually apply to before getting one, Especially out of college. Do response times/rates differ for different career fields? I'm trying to get a job in either a human resources position or a communications/PR position and so I wonder if that has anything to do with response times.

Thanks!

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