Is there a time limit in which to expect the paperwork to come to my house for a speeding offence? Its been 17 days since I committed the crime of the century and still waiting for the postman? 
The 14 day ruling only applies to times you aren't stopped at the scene of the crime - such as a speed camera offence. Since you were stopped at the time, and the identity of the driver was established at the scene (you showed your license) then the time limit that applies is 6 months. It's not a guideline, or a rule - it's the
LAW . Section 127 of The Magistrates Act 1980 :
http://www.legislation.gov.uk/ukpga/1980/43/section/127The usual progress (provided your speed wasn't stupid) is for you to be sent a "Conditional offer of a fixed penalty" - aka CoFP. This gives you the option of pleading guilty to the offence at the earliest opportunity, and accepting the 3 points and £100 fine. You have 28 days to accept that offer. You can either accept this, decline and fight, or ignore (which will be treated as decline and fight eventually). If you ignore, you may get a reminder - but don't rely on it - they don't have to issue reminders.
Once you've ignored/declined the CoFP, the CPS have to 'ley the information' before the courts within 6 months from the date of the offence. The courts will then issue a summons which will be sent to your last known address. Thus may take a few days/weeks to process after the information is "leyed", so you aren't really safe for about 7 months.
If the CoFP arrives after month 5, then you can wait the 28 days, and by the time the CPS realise you're ignoring them, they will be outside the 6 months limit to ley the information and go through the courts.
If I were you, I'd just sit tight, and wait to see what the postie brings.