Pindiri glacier and roopkund

I've done both those treks in autumn (right season: september 15 till october 31). In the spring, it's also OK. You must avoid the monsoon season.
Pindari: there is some accomodation along the trail, however this trek is very popular with Indian tourists and in high season the rest houses will be extremely crowded. You can get meals too.
Roopkund: there are also rest houses at low altitude (Wan, Kanol), these get full in high season as well. At Bedni Bugyal, you can find accomodation in some shacks. However, it's better to have your own tent. Above Bedni Bugyal, there is nothing at all. If you can manage it, I recommend you to cross the Junargali Pass just above Roopkund and go down on the other side: that's a really wild valley, absolutely fantastic.

Theres not much that I can add to the last post, the Pindari trek is much busier than Rup Kund (much easier !) ,I trekked to the Pindari glacier and Sunderdhunga in 1995 in October and met just one other trekker ,an Australian, I guess times have changed! Indeed the best time is October ,November is also fine,wonderful clear views, just be prepared for the colder nights although Rup Kund may already be snowed up . The early summer, June / mid July is also good although the peaks cloud over in the afternoon and we had to wade through snow and ice going up to Rup Kund in late June from BedniBugyal. There is a camping place above Bedni Bugyal( Bogya basa)(Stone huts) with great views, better to rest there imo and early in the morning carry on to RKund and back( or further) . A tent and provisions is essential if you are going to Rup Kund , I found a great guide in Gwaldam, without whom my trip to Rkund and over the pass (junargali) would have been impossible( I was alone ), Pindari is, however ,( relatively ) a breeze and no guide is neccessary. Enjoy !

ps A tent is handy if rest houses are full , plus I preferred to sleep out rather than in the rooms which were pretty dire !

pps Be aware that the monsoon can drag on and if you can, avoid September and wait until October, for Pindari ,November is lovely.