Powerchains are normally used when you are in a continuous strong steel archwire.
These thick heavy wires can only be inserted once the initial levelling and aligning with soft flexible wires has been completed.
Most orthodontic cases (including extraction cases) start with soft wires and move up into heavy wires progressively. Depending on the severity of your initial crowding, it may take a few months.
If you had extractions done at the beginning, you may have to wait awhile before you can start closing the extraction spaces. Also, since the extractions were done 8 months ago, the bone in the extraction site has matured and this can make it more difficult to move teeth through it.
Sectional mechanics can be used to close extraction spaces right from the start. This is a more advanced technique and is extremely efficient when used correctly.
Depending on how the extraction spaces are being closed (moving only the canines first vs en-masse retraction), the rate of space closure will vary. This may also account for why the spaces are still open at this point.
I would be patient, since you are trying to close a tooth-sized gap on either side of your mouth. Trust me, your dentist also has their eye on the spaces!
