Is there a time limit for how long you can hold funds for? 1 month? 3 months?
There is no minimum but gifts are determined to be appropriate in the stated rules below with regards to time limits.
RULES:
3. I am not a bank. Escrows are for a period of 30 days and an additional 1% gift (or BTC minimum if higher) will be required for each 30 day period thereafter.
I have also just updated this rule to add, "(or BTC minimum if higher)" but it should be noted that I am not as strict as you might believe with these rules. They are mostly there to protect me against overly long holding times or infinite liability with someone else's funds if they are never claimed.