The Khands mentioned in Japn Ji Sahib are spirtual stages, NOT physical stages or places.
Please refer to the Prof Sahib Singh Ji's steek online available at :
http://www.sikh.net/Gurbani/Darpan.htm
Akal sahai
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/interfaith-dialogues/209-heaven-and-hell.html
Babbar Sher