Trick to avoiding future dates in order to reach higher delays
1. First find the seed of your desired pokemon, whether it's available on
http://dppt.x-treem.nl/ or in the RNG Reporter, DPPt Time Finder, DPPt capture section.
2. Make note of desired seed, then from the RNG Reporter click "Seed To Time", enter your seed, year = 2009, then click generate, and it should list all the dates, time & delay that your seed is available. What I normally do is choose a date where there's the most frequency. For example, seed 390F02B8 occurs 52 times on 6/1/2009 between 15:00:51 and 15:51:00 and has a 59 second gap in between in order to retry hitting that delay of 687 over and over again.
3. To hit the delay of say 687, then it be wise to beforehand synchronize your DS clock with at least the minutes and digital seconds from your clock or watch, then go to a patchy grass area and capture any pokemon and use any method possible to accurately obtain its IVs. I use an AR for IV checking so it's much quicker for me that way. To get an idea of what delay you are hitting, click DPPt Seed Finder on the RNG Reporter, enter the DS year, month, date, hour, minute from the time you pressed "continue" when you started the game to go capture, along with your captured pokemon's nature and IVs, then press find. Look for the line where type = "Initial", then note that Seconds is when you "actually" pressed the continue button, and the delay is how long it actually took for you to press start until you pressed continue. If your delay is an even number and your target delay was odd, then insert any GBA cart. Same applies if your target delay is even and you're hitting an odd delay.
4. Ok, now you should be able to start determining how to hit your delay. Normally if you keep pressing A from start to continue constantly you should hit a delay in the low 600's, but to extend it, do the exact same thing but in platinum when you hear giratina roar, or in diamond and pearl after the 2nd chime, pause for up to a second or 2, and then press the "continue" button. This obviously takes some practicing to do and the better you get at it you can reach those hard to reach delay.
For the record, all my recent RNG catches had dates from 5/6/2009 and 6/1/2009 and delays ranging from 622 through 734 in 2009.