So sorry for your loss
It depends from person to person - after a mc ( including d&c ) your hormones can be off kilter ( or not - some people revert to normal straight away ). The other issue is that due to hormones potentially being out of kilter you can't really depend on ovulation tests - as it is these hormones that may be out of kilter - so you can get false positives - in fact the only way you can kind of be sure of when you ov is the point at which you get your AF - as ov is generally 2 weeks previous ( and again this isn't definitive as some people can have a short luteal phase ) .
Your 1st couple of cycles may be off - you may find you have longer or shorter cycles than previously ( eg mine were 29days pre mc, post mc were 35days, 34 days, 27 days then 26 days - the next cycle after that I got pg ) some people have longer cycles again - anything up to 8 weeks.
If you want to ttc straight away then best bet is to bd every other day and not stress about opk testing ( just as it can't be necessarily depended on and you won't know which category you fit in ) . Also - try to relax about it - you can get pg symptoms after mc due to potential hormonal inbalances which obviously if you are ttc again can cause a little worry when you will probably be feeling a real drive to be pg again.
There's no real reason to not starting ttc straight away - unless you have been advised of a medical reason ( and of course you feeling ready to try ) . The only possible argument for waiting after a D&C is that they can scrape the lining quite thin and it may be worth giving it a chance to recover - but to the contrary plenty of ladies still have successful pg straight after a D&C.
Ultimatley you need to weigh it all up and if you decide to just go for it - there is so much support on the TTCAL forum - and they will understand everything you're feeling and going through following this very sad time
hope you get your sticky BFP
hx
hx