HP Timeline: Neville, Harry, Spoilery

[Milz]

Hi all. I'm a long time member, but first time poster.

After reading HBP, I have some concerns about the Timeline, 
specifically the years 1979 to 1981. I'm using the Timeline at the 
Lexicon as a reference. I'm looking at the time between 
the Prophecy (precise date unknown) and October 24 1981 when Peter 
Pettigrew is made the 
Potter's Secret Keeper.

http://www.hp-lexicon.org/timelines/main/timeline_1970-1990.html
 
Per HBP, Dumbledore knows that the child born in July is "the 
child".  Per the Lexicon Timeline, Dumbledore has this information at 
least 1 year before Oct. 24, 1981. Unless wizarding pregnancies are 
different than Muggle pregnancies, in early 1980, Dumbledore knows 
that Lily Potter and Alice Longbottom are pregnant and the estimated 
delivery dates are late July to early August.

Logically, Dumbledore would have put these expectant families under 
protective services as soon as he had that prophecy information. As 
far as I can tell, the canon isn't specific to the month when the 
Prophecy was made, so we don't know the proximity of the Prophecy to 
the births of Neville and Harry.

Anyhow, Neville and Harry are born and presumably the Longbottoms and 
Potters are in safe houses during the remaining months of 1980 to 
Halloween 1981. 

According to canon, Peter Pettigrew is made the Potter's secret 
keeper on  October 24, 1981. IIRC in PoA, Harry learns that 
Dumbledore offered to be their secret keeper before they went into 
hiding but James wanted Peter to be it. 7 days later, the Potters are 
dead and Voldemort is defeated.  

So, my question is, what is the date of the prophecy? I can't imagine 
that Dumbledore or the Ministry would wait for 1 year before putting 
the Potters and Longbottoms in safehouses.

Milz