With the increased processing times, could you give us a sense as to how long will it take for our clients to get a conditional green card?

USCIS is showing 32 to 49 months of processing time for the I-526. At this point, clients should realistically expect 36 months for this first stage.
As for the adjustment of status, or the consular interview, whatever the case might be, depending on whether the client is applying for the green card in the US, or from overseas, it is safe to say that they should budget another nine months, or so. So, within approximately four years, assuming no retrogression issues to deal with, they could get their green card.
To apply for the removal of conditions, they need to wait for another two years, which is commonly known as the sustainment period. Ninety days before the end of the sustainment period, the investor could file for the I-829. If the terms on the private placement memorandum allow, or if the regional center is willing to pay back, then they could receive their capital back soon after that. So, the total time for them to get their capital back would then be three years for the I-526, another one year for the conditional green card, and another two years for the sustainment period making the total six years. Assuming all the assumptions above work out, at the end of these six years, they could get their capital back.
As for I-829 approval for removal of conditions from the green card, USCIS is showing 23.5 to 54 months. So, the best-case scenario for this phase would be another two years, making the total number of years to receive a permanent green card, eight years.