Frames can be a nuisance in Diamond... The egg IV frame sporadically advances based on the NPC movement, including the Pachirisu's movement. Prepare to hate cowgirls.
Save next to the old daycare man as he is holding your proper (shiny) egg. You should discover your current save frame after calibrating; i.e. pick an egg IV spread, synchronize clocks, aim for the target seed (the date+time+delay), receive egg quickly, verify what seed you hit through coin flips, and see how far off from your target seed you actually are. After you figure out how far off you were, you should (fast) hatch the egg and check its IVs (either code or rare candy / daycare to level 10-15 stats with metalkid's IV calculator) to determine what save frame you were on upon talking to the daycare man (you do not have to blaze through his speech, just rush to interact with him by pressing A). Consider my examples and what you should do from there...
If your target frame is 6 and your save frame is 3, simply reset and resave next to the old man. You can keep repeating this process (calibrate, check, reset, resave) until you are confident that your save frame is your target frame (in this case, frame 6). Then, proceed with hitting your target seed. You never want to agonize over hitting your target seed and then discover that the frame you are currently saved on sucks, imo.
If your target frame is 6 and your save frame is 2, simply reset and you may advance the calender and utilize the journal (+2 egg IV frame advancements per page with a "battle/capture/defeated" phrase). Pick a new egg IV spread in the future/past with an even frame. If you pick target frame 6, you would flip the journal twice (assuming these pages have that mentioned phrase) and then take the egg. If you pick target frame 8, flip the journal 3 times.
If your target frame is 7 and your save frame is 5, you can also use the above journal method. Just find a new spread on another date with an odd target frame. Even searches for other even frames; odd searches for other odd frames. Do some math blah.
(Target Frame - Save Frame) / 2 = Number of Journal Flips
Check out da guide if you have not. God forbid if I confused you more. :C