After some thoughts I decided to upgrade schematics with energy harvesting IC, in case if there won't be enough high voltage generated after diode voltage multiplier. On other hand, if there appears excess of energy, it must be stored and regulated.

There are many great options available at the market from TI, Analog Devices. I've selected LTC3108 from former Linear Technology, because I had in my component box 2 samples of these, which I obtained 6-7 years ago :)

Speaking about layout - I decided to make it as modular as possible, by using breakout special lines of drills in PCB:

1) Antenna part - it can be easily braked out, in case if I'll decide to choose another one, i.e. made of other material (copper wire) or for harvesting other frequencies (i.e. 915MHz).
On silkscreen layer there are marks at antenna, that will help to fine-tune its length symmetrically (I've made it equal to  length 1/4 of wavelength for 2.40GHz wave)

2) Voltage detector circuit - at the moment I'm not sure that it 100% satisfy the goal of the project: there are assumptions, that must be confirmed experimentally. I added pi-matching circuit for fine tuning antenna later;

3) Energy harvester - I decided to make it independent and reusable/reconfigurable: by swapping R3 and R4 jumper position it's possible to set output voltage. Moreover, this PCB part is reusable and can be used with TEG, solar panels, photodiodes in other projects

As result, PCBs and components are ordered and I'm waiting them now.