US market - VOO or CSPX QQQ or CNDX or anything else?

I’m looking at CSPX/VOO, CNDX/QQQM and SMH, but I’m open to other ETFs too. My main confusion is whether this is a good time to start. The US market looks quite expensive right now and there are a lot of concerns about AI/tech valuations and a possible correction. If you were in my position, would you start investing now and spread it over 3–4 months, or wait for a correction? And which ETFs would you personally pick? Also, for someone investing from India, is UCITS generally preferable to US-listed ETFs? And does doing a monthly SIP/DCA make sense, or do FX, brokerage and other charges make small purchases inefficient?