I got a set of neck beads and a japa mala of tulasi. I want to wear the neck beads; of course I know it would be permanent. I got two sets, an 18" which may be too tight, and a 48" which will go around twice at 24" which is very good. I can also string them together to go around three times at 22" which is even better.

I found instructions on how to offer them to Lord Krishna before using. I've also found conflicting information on how many times to go around the neck. But conflicting is as conflicting does, i.e., everyone has an opinion.

This is the article about offering:

Japa-mala and kanthi-mala must be purified and offered before they are taken into use. The rite of sanctifying the mala should performed by gurudeva or another senior Vaishnava. In their absence, one may also do it himself.

To purify the mala, you should first bathe it in sacred water. Then, place it on a tray and bathe it with pancha-gavya, or the five substances of cow (milk, yoghurt, ghee, cow dung and cow urine), followed by the pancha-amrita, or the five nectarine substances (milk, yoghurt, ghee, honey and sugar-water).

Having completed the bathing, chant the eighteen-syllable Krishna-mantra and the kama-gayatri eight times each over the mala. Then, worship the mala with the touch of the fumes of incense, chanting the sadyojAta-mantra:

sadyojAtaM prapadyAmi sadyojAtAya vai namo namaH |
bhave bhave nAtibhave bhavasva mAm bhavodbhavAya namaH || mnu 17.1

I seek shelter in the giver of new life, I salute him again and again. Do not leave me amidst the mundane world, lead me beyond; Obeisances to the one at the source of the worlds!

With this rite, new life is invoked into the mala for the deliverance of the sadhaka. Before employing the mala, one should pray to the sacred mala, offering it to Krishna. One should never employ a mala without offering it first:

haraye nArpayed yas tu tulasI-kASTha-sambhavAm |
mAlAM dhatte svayaM mUDhaH sa yAti narakaM dhruvam || hbv 4.310

That fool, who accepts the mala made of tulasi-wood without offering it to Hari, will attain a permanent hell.

Having duly offered the mala to Thakur by wearing it around his neck or touching it to his hand, and then touching it to the heads of his companions and the guru-varga, one may employ it himself. If a kanthi-mala has been sanctified, it should be bound around the neck with the following mantra:

tulasI-kASTha-sambhUte mAle kRSNa-jana priYe |
bibharmi tvAm ahaM kaNThe kuru mAM kRSNa-vallabhaM || hbv 4.312

Born of the branches of Tulasi, mala, dear to Krishnas people; I carry you in my neck, make me dear to Krishna.

If a japa-mala is been sanctified, it should be taken with folded hands and placed into the bead bag with the following prayers:

avighnaM kuru mAle tvaM hari.nAma-japeSu ca |
zrI-rAdhA-kRSNayor dAsyaM dehi-mAle tu prArthaye || mbd 4.223

O mala, I implore you: Make my harinama-japa free of obstacles, bestow me the servitude of Radha and Krishna!

tvaM mAle sarva-devAnAM sarva-siddhi.pradA matA |
tena satyena me siddhiM dehi mAtar namostu te || mbd 4.225

You, O mala, we know as the abode of all gods and the bestower of all perfections. Thus, verily, bestow perfection unto me; Obeisances unto you!
I don't have access to cow dung or cow urine. I can make a panchamrit to bathe them with, and I can say the prayers. But I am wondering if it's also OK to put them on the altar when I do puja and offer panchamrit (without bathing them) and other offerings, then accept them as prasad just like the panchamrit and other offering(s), and use them.

Now, I'm not Gaudiya or ISKCON, but I thought wearing the tulsi neckbeads would be a nice gesture to show devotion to Sri Krishna, not to mention using the mala for japa.