I don't see where is the problem. Simple

You received 60 BTC which is a lot in stage 1. That should get you a head-start and to get trust from investors :

1. Pay the bounties from stage 1 you will be left with more than 50 BTC
2. Release the wallet and distribute the coins if you think you got much less than you wanted well that's a risk every developer has to accommodate sometimes less is more in crypto ( a lot of now sucessful projects even started as a joke and are now in top 50 coins without any starting funds) apart from that I'm OK if you take that 9% that was reserved for PoW as development fund and that should give you motivation for your project to be properly developed.

Now for the escrow :

1. You get 20% of escrow when you distribute coins and post working basic wallet along with source (that's additional 15-18 BTC I don't know how much was raised in stage 2 )
2. You get 20% when you list it on Bittrex and not some shitty exchange (3 BTC listing fee will get you additional 15 BTC for development)

You are still left with more than 80 BTC (stage1+stage2) you can start developing the wallet you promised.

3. You get 20% when you release wallet you promised (beta one)
4. You get 40% when it's functional (I'm not saying smart contracts, debit cards, ... ) but that it is stable