Change out modem without upsetting FTTC DSLAM

All going to plan my FTTC connection will be installed in a few days time.
Its a new (second) line and Zen have told me its an Engineer install and the Engineer will provide a modem.

I have read (on these forums) that during the training period (is it 10 days?) it is not good to switch off modem or reboot it as the DSLAM may see this as a problem on the line and throttle back the connection.

What is the best way to change out the modem for a modem/router without upsetting the DSLAM?

If you have the modem ready for day 1 of the install then just use it.

Nothing worthwhile is set in stone by this magical 10 day period. The FTTC DLM will take its most drastic action in the first day or two, but the algorithm never stops running.

So whenever you swap out kit best to do it gracefully e.g. power down to allow last gasp message and then plug in cleanly, don't go plugging in/out 10 times in 5 minutes.

Power it off, swap the modems, power it on. It's best to do this on day 1, within 24 hours after the install.

Wait till the end of the day after it is connected, as long as it is connected for over 15 minutes on the first day. Then (within reason) do what you like. The 10 days is a BT Wholesale myth and not mentioned anywhere by Openreach, who control the connection and provide the DLM.

Dynamic Line Management (DLM) is employed in GEA-FTTC. DLM constantly manages lines to maintain a target link quality (speed and stability). It does this for as long as the product exists.

At provision, the line is put on �wide open� VDSL2 line profiles allowing the upstream and downstream line speeds to run at the upper limit of the product option selected.

On the first day of operation, DLM will intervene if severe instability is detected. Otherwise, DLM will wait until the day after provision before deciding if it must intervene, provided that the line has been trained up for at least 15 minutes during the preceding day.

From Openreach SIN 498.

Bear in mind you may need to use the Openreach modem in the future, either for diagnostics or if your modem/router fails. So don't bin it or sell it.

Thanks guys.
I have no intention of selling the modem and will keep it around for future testing or diagnostics.