You will hear all kinds of different opinions on this one. Every animal is different.
If you have the facility to keep them apart for 2 weeks or 2 months, why not keep them seperated until she is bred or ready to breed.
IF you put them back together & she/he goes back to sucking, than you may NEVER get that calf weaned. If it aggressively sucks the cow, yes she can get her to come to milk - a sucking calf can get a heifer that has never calved come to milk. And even if they don't come to milk, the chance of mastitis is very great.
Also, if the calf is sneaking a little suck (which you may NEVER know), when the cow bags up for her next calf, the yearling will suck out all her colostrom & the newborn will not have it.
Too many "ifs" if you put them together too soon (and what's too soon). I keep them apart until they are bred. I've never had a problem with that program.